This article assumes the Regulative Principle of Worship (RPW), which is the biblical doctrine that everything of religious significance in worship must be prescribed in holy Scripture, either explicitly or by good and necessary consequence, such that “whatever is beside the Word of God is against the Word of God.”  Given the RPW, the case for Exclusive Psalmody need only be made by demonstrating that the Bible commands the singing of Psalms in worship and simply not finding a command to sing anything else. The Bible does not need to explicitly say “sing Psalms exclusively,” and it does not have to explicitly forbid all human composed hymns, it just has to prescribe Psalm singing and not prescribe anything else.
1) Inspiration is a necessary qualification for writing worship songs.
The pattern of Scripture, from beginning to end, is that worship songs were always composed by the inspiration of the Holy Spirit, either for temporary and special occasions, or for perpetual use in public and private worship. “There is a biblical connection between prophecy and praise. There is no warrant in Scripture for the use of uninspired human compositions in the singing of God’s praise in worship. Those who wrote songs to be employed in worship knew that they were prophets and were self conscious that as prophets they were providing inspired words to be sung.” (Robert McCurley, The Singing of Psalms).
Here is a brief overview of sung praise in Scripture:
V. When was praise first publicly given to God by the church?
We read of it first at the shores of the Red Sea, when “the church” (Acts 7:38) was delivered from her enemies. Exod. 15:1.
VI. When did praise become a stated part of divine worship?
More particularly when the worship of Jehovah was established at Jerusalem, in the days of David, who spake as he was moved by the Holy Ghost; and is called by God, “the sweet psalmist of Israel.“2 Sam. 23:1-2; 1 Chron. 15:16, 19, 27.
VII. Was praise subsequently a part of divine worship?
Yes. Psa. 100:4; 84:4; 43:3, 4; Col. 3:16; Eph. 5:19.
VIII. Did David, as the psalmist of Israel, write all the psalms?
No. He wrote probably more than one half of them. Yet they are called by his name (Heb. 4:7; Rom. 11:9) because he was employed more extensively than any other, in this part of the word of God, as the amanuensis of the Holy Ghost.
IX. What name was originally given to that part of the Holy Scriptures which is thus called David?
It was called “Tehillim,” that is, hymns or praises, because it was given as the matter of divine praise to the church of God in every future age. It is also called “Psalms,” because many of these “spiritual songs” were, at the temple worship, sung with the psaltery. Parts of the book have other names, as Mizmor, Shir (46, title), Tehillah (145, title), Tephilah (17, 86, 102, titles), Prayers, Shir-hammacholoth (120-134) – Odes of Ascension. They are also called, in the Septuagint, Psalmoi.
X. When were the Tehillim, or Psalms written and formed into a book?
They were written in a manner similar to the other parts of Scripture Heb. 1:1, during a period of nearly one thousand years, and were collected into one book, probably by “Ezra the priest, a scribe of the law of the God of heaven.” They stood in their present numerical order in the days of the apostles. Acts 13:33.
XI. Were other songs, beside those contained in the Book of Psalms, composed during that period?
Yes, many. Such as the Song of Deborah Judg. 5:12, the song of the well Num. 21:17, 18, the 1005 songs of Solomon, and others.
XII. Were not these then given as the matter of her praise, or are they not commanded to be sung by the church in all future ages?
No. As we read of different books in Scripture, such as the book of Gad, of Nathan, of Jehu, of Jasher, and the Epistle from Laodicea, which were not collected into the sacred canon, by the Holy Ghost, so we thus know, that by the same divine sovereignty, the songs thus noticed, or even recorded, were ephemeral as matter of praise; while the songs contained in the “Sepher Tehillim,” or Book of Psalms, and collected and placed in one book by the Spirit, are a part of “the word of God, which liveth and abideth forever,” selected by infinite wisdom, and given expressly as the matter of praise to the church until the end of time. The same principle applies to any isolated and occasional hymns or songs, which may be found in the New Testament.
Alexander Blaikie, A Catechism on Praise
Moses, the greatest Old Testament prophet, composed Psalm 90, and was commissioned by God to compose another song in Deuteronomy 31:19. Prophetesses Miriam (Ex. 15) and Deborah prophesied in song (Judges 4:4; 5:1). The company of prophets prophesied in song (1 Samuel 10:5).
“Now these be the last words of David. David the son of Jesse said, and the man who was raised up on high, the anointed of the God of Jacob, and the sweet psalmist of Israel, said, The Spirit of the Lord spake by me, and his word was in my tongue.” 2 Samuel 23:1-2
“The man who was raised up on high” includes the Hebrew word for oracle, which refers to revelatory utterances of Jehovah. David was a prophet (Acts 2:29-30) and inspired by the Holy Spirit (Acts 1:16) to write worship songs for perpetual use in the Church.
“Moreover Hezekiah the king and the princes commanded the Levites to sing praise unto the Lord with the words of David, and of Asaph the seer. And they sang praises with gladness, and they bowed their heads and worshipped.” 2 Chronicles 29:30
Hezekiah, Josiah, Zerubbabel, and Nehemiah restored the Old Testament Church’s worship, which included a return to the songs that had been given by the prophets for public worship (2 Chron. 29:30; 20:21-22; 23:18; 35:15; Ezra 3:10-11; Neh. 12:45-46).
A seer is a prophet, “he that is now called a Prophet was beforetime called a Seer” (1 Samuel 9:9). Worship song was produced by prophecy (1 Chron. 25:1-7). Asaph the Seer (2 Chron. 29:30), Jeduthun the Seer (Psalms 39, 62, and 77; 1 Chron. 35:1; 2 Chron. 35:15), Heman the Seer (1 Chron. 25:5), etc. were appointed by God to compose a canon of worship songs for perpetual use in the Church.
For every example and command we have to sing in Scripture, the content was written by those who “were moved by the Holy Ghost” (2 Peter 1:21).
“Inspiration is a necessary qualification for writing worship songs, it belonged to the prophetic office. There is no warrant in Scripture for the use of uninspired human compositions in the singing of God’s praise in worship. This standard is carried forward as the expectation into the New Testament. No other songs are provided.” (Robert McCurley, The Singing of Psalms).
“Asaph, Heman, and Ethan, were men indued with an infallible measure of a Spirit of prophecy, in inditing [composing] those Psalms, which the Church of Israel received from them. Give us the like men with the like gifts, and we shall receive their Psalms, as the Church of Israel did the other.”
John Cotton, Singing of Psalms a Gospel Ordinance (1647), p. 27.
Then we come to the New Testament and see Christ and the Apostles singing praise from the completed canon of songs given by the Holy Spirit (Mat. 26:30; Mark 14:26; Acts 16:25; James 5:13). Westminster Divine John Lightfoot appeals to the sufficiency of the Psalter and points out that God could have appointed more worship songs to be written for the use of the Church if there needed to be, but even our Lord was content with them:
“Here [Mat. 26:30] the Lord of David sings the Psalms of David…He that gave the Spirit to David to compose, sings what he composed. That all-blessed copy of peace and order, could have indited himself, could have inspired every disciple to have been a David, but submits to order, which God had appointed, sings the Psalms of David, and tenders the peace of the Church, and takes the same course the whole Church did… If you sing right, sing David’s Psalms, but make them your own. Let the skill of composure be his, the life of devotion yours.”
John Lightfoot, Works, vol. vii, 1 Cor. 14:26: “Everyone hath a psalm,” pp. 40-43.
“How is it then, brethren? when ye come together, every one of you hath a psalm, hath a doctrine, hath a tongue, hath a revelation, hath an interpretation. Let all things be done unto edifying.” 1 Corinthians 14:26
1 Corinthians 14:14-26 describes revelatory prophecy being given in charismatic utterances in song similar to the Old Testament examples we’ve just seen. This was not corporate singing, it was delivered by individuals extemporaneously. But this gift was temporary. The Church is not now able to produce inspired texts. The temporary office of prophet has expired and the production of inspired texts has ceased. Without the office of prophet there can be no composing of worship songs. We have no more warrant to substitute the canonical text in singing than we do in reading.
“The New Testament use of the Psalms verifies that the Psalms are provided for permanent use. There is no gift given in the New Testament for inspired praise, no command to compose it, no evidence of new songs in the New Testament, no command to write uninspired praise.” (McCurley, ibid.).
Objection: Ministers compose sermons and pray prayers in their own words, therefore we can use our own words to compose hymns for worship.
Answer: When God prescribes an ordinance, he defines the content for that ordinance. God has given a permanent office of ministry to the Church, pastors, who are to explain the sense of the Scripture, “rightly dividing the word of truth” (2 Tim. 2:15). “While we are to acknowledge God in all our ways [Prov. 3:6], and to ‘pray without ceasing‘ [1 Thes. 5:17], he has, by one short and perfect form, said, ‘after this manner pray ye‘ [Mat. 6:9].” (Blaikie, ibid.). In truth, there is no example or command to bring our own human composed songs before God as worship like there is for using our own words in preached sermons (Neh. 8:8; Mat. 28:19-20; Luke 24:47; 2 Tim. 2:15; 4:2) and in prayers (Mat. 6:9; Rom. 8:26; Phil. 4:6; 1 Tim 2:1-2; 1 John 5:14). There is no canonical book of prayers or book of sermons, but there is a canonical book for reading (the Bible), and for singing (the Psalms).
Objection: Song is not an element of worship but rather a mode of prayer, teaching, or exhortation.
Answer: Singing praise to God does indeed teach us about him and what he requires of us (Col. 3:16) and consists of solemn addresses and supplications to God (Ps. 55:1), but not as an indifferent manner of performing other acts of worship because singing praise is itself an act of worship prescribed by Scripture (Ex. 15:21; 1 Ch. 16:9, 23; Ps. 9:11; 30:4; 33:2, 3; 47:6, 7; 66:2; 68:4, 32; 81:1; 95:1; 96:1, 2; 98:1, 4, 5; 105:2; 135:3; 147:7; 149:1, 3, etc.).
Secondly, God defines the parameters for the ordinances that he prescribes. Applying the parameters of one part of worship to another leads to absurdities and the critic making this argument does not actually worship this way consistently. For instance, if singing is a mode of prayer, teaching, or exhortation, then only ordained men may sing. Instead of preaching sermons, ordained men can sing them. The entire worship service could be sung, or none of it could. Or, since women ought to sing, then women may also preach and lead in prayer, which contradicts various passages, e.g. 1 Tim. 2:12; 1 Cor. 14:34-35.
Objection: Scripture repeatedly speaks of singing a “new song” (Psa. 33:3; 40:3; 96:1; 98:1; 144:9; 149:1; Isa. 42:10). The four beasts and 24 elders sang a “new song” (Rev. 5:9), the 144,000 followers of the Lamb who had gotten victory over the beast also sang a “new song” (Rev. 14:3). Therefore, we may (or should) compose new songs for public worship.
Answer: When we come across the exhortation to “sing (not compose) a new song” in the Psalms, it is not telling us to stop singing the psalm and to go write a “new” song, it is telling us that that psalm itself is the “new song.” Matthew Poole comments on Revelation 14:3 regarding the intended sense of “new song” used in Scripture, “And quite through the Scriptures generally, a new song signifies a song which praiseth God for some new benefits received from him.” Poole also comments on Psalm 33:3, “So this song is here called new, not so much from the matter, as from the singing of it; because sung afresh, or again.” Hence, the exhortation to sing a new song does not provide sufficient warrant to compose our own worship songs. Read a more detailed treatment of this topic here: Psalmody Objections Answered: “New Song”.
2) The Purpose of the Book of Psalms.
God uniquely designed the Book of Psalms not only to be read, as other books of the Bible, but also to be sung. It is designated “Sepher Tehillim,” meaning Book of Praises and Scripture repeatedly entreats us to sing psalms (1 Ch. 16:9; Ps. 95:2; Ps. 149:1; Ps. 105:2; Col. 3:16; Eph. 5:19; James 5:13, etc.). Additionally, we’ve seen how the Psalter was developed and used by the Church in the Old and New Testaments, further demonstrating the purpose of the Psalter to be sung. The Holy Spirit has inspired and compiled the material for fulfilling the command to sing praise unto God, our job is to receive it and use it as intended, not adding to it nor taking away from it.
“Scripture provides, and we possess, a deposit of inspired songs in the canon and directs us to use that text in worship. Therefore the Book of Psalms has a unique and authoritative status, we are restricted to what God made available in the Bible. The Book of Psalms itself tells us that it is intended for the worship of God. A divine provision of a collection of inspired songs in the canon constitutes prescription. The mere existence of the Psalter in the canon proves that it is a distinctive element for the worship of God. The Bible’s own provision of a canonical text for reading and a canonical text for singing are irrefutably connected to one another.” (McCurley, ibid.).
“The Scriptures contain many commands to praise God by singing (Ex. 15:21; 1 Ch. 16:9, 23; Ps. 9:11; 30:4; 33:2, 3; 47:6, 7; 66:2; 68:4, 32; 81:1; 95:1; 96:1, 2; 98:1, 4, 5; 105:2; 135:3; 147:7; 149:1, 3, etc.).”  God instituted worship song as a permanent ordinance in the Church, so the inclusion of the Book of Psalms in the canon demonstrates the provision of the content for this ordinance. It is not as though God commanded us to sing but did not provide us with a sufficient text to sing.
The Psalter was made to be sung in worship. It’s mere presence in the canon of Scripture constitutes a command to sing its songs. Therefore, the burden of proof is on those who would posit that we may sing anything else, because Scriptural warrant must be given to introduce anything into the worship of God. Sufficient warrant can be found to sing the Psalms, but there is a lack of proof that Scripture prescribes the singing of anything else, especially songs composed without the inspiration of the Holy Spirit, which has never been the rule for God’s people.
When Hezekiah, Josiah, Zerubbabel, and Nehemiah restored the Old Testament Church’s worship, they did not go back to singing the songs of Miriam, Deborah, etc., rather, they sang “praise unto the Lord with the words of David, and of Asaph the seer” (2 Chron. 29:30; c.f. 2 Chron. 20:21-22; 23:18; 35:15; Ezra 3:10-11; Neh. 12:45-46). Even though the former songs are inspired by the Holy Spirit, they were not compiled into the Psalter by him and were evidently composed and sung for a particular purpose rather than for perpetual use; also the godly kings did not compose new songs without the prophetic gift, rather they found the canonical Psalter sufficient for the content of sung praise. Hence the godly kings recognized the canonical status of the Psalter, even though the Psalter was still not complete yet for some of them.
“When we say that the Bible’s canonical song book must be supplimented from materials outside of the canon, that the canon itself does not provide for what we need, we are saying the Bible is not sufficient.” (McCurley, ibid.).
Objection: The existence of songs outside the Book of Psalms in Scripture proves Exclusive Psalmody wrong.
Answer: Although there are other scriptural songs outside the Psalter, and songs have been sung under the inspiration of the Holy Spirit that were subsequently not recorded in Scripture, these songs were not compiled into the Psalter by the Holy Spirit and evidently were only intended for temporary use. Much less do the existence of scriptural songs outside the Psalter provide warrant to compose uninspired songs.
“Until the final collection and close of the Psalter along with the rest of the Old Testament canon, probably during the time of Ezra and Nehemiah, the question of the exclusive use of any book of songs is out of place. The Psalter was not closed until the Old Testament canon was closed. To raise the existence of these songs as an objection to exclusive psalmody makes about as much or as little sense as appealing to passages like 1 Corinthians 5:9 and Colossians 4:16 for the authority to preach from non-canonical materials. We freely grant that some songs were sung in Old Testament worship which were not finally included in the Psalter, just as we grant that Paul wrote some letters which functioned authoritatively in the Church but which were not finally included in the canon of Scripture as we now have it.” (Michael Bushell, Songs of Zion, p. 189).
3) Sufficiency of the Psalter.
“The character of the Book of Psalms as a permanent manual of praise is sufficient to fulfill the command to sing praises in worship; no other content is needed. The canonical Psalter is used in light of a completed New Testament canon, which casts light on the fullness of the meaning of the Book of Psalms. The New Testament quotes the Book of Psalms more than any other book. On average, Psalms is quoted once every nineteen verses in the New Testament.” (McCurley, ibid.).
For example, Hebrews 1, one of the most Christ centered chapters in the New Testament, quotes the Psalms seven times. Not only is the Book of Psalms Christ centered, it is experientially focused, it gives us every facet of Christian experience, and in proportions you will never find in an uninspired hymn book. (c.f. The Marcions Have Landed, and What Can Miserable Christians Sing? by Carl Trueman). (McCurley, ibid.).
“Each of these books [of the Bible], you see, is like a garden which grows one special kind of fruit; by contrast, the Psalter is a garden which, besides its special fruit, grows also some those of all the rest…”
“It is possible for us, therefore, to find in the Psalter not only the reflection of our own soul’s state, together with precept and example for all possible conditions, but also a fit form of words wherewith to please the Lord on each of life’s occasions…”
“So then, my son, let whoever reads this Book of Psalms take the things in it quite simply as God-inspired; and let each select from it, as from the fruits of a garden, those things of which he sees himself in need. For I think that in the words of this book all human life is covered, with all its states and thoughts, and that nothing further can be found in man. For no matter what you seek, whether it be repentance and confession, or help in trouble and temptation or under persecution, whether you have been set free from plots and snares or, on the contrary, are sad for any reason, or whether, seeing yourself progressing and your enemy cast down, you want to praise and thank and bless the Lord, each of these things the Divine Psalms show you how to do, and in every case the words you want are written down for you, and you can say them as your own.”
Athanasius (296–373), Letter to Marcellinus on the Interpretation of the Psalms
“We know more about the internal experience of Jesus on the cross from the Book of Psalms than we would ever know from the four Gospels. It’s a Christocentric book. All of the offices of Christ, the humiliation, exaltation, all of the various functions and aspects of his redemption, it is all there, there is nothing missing. God knew what he was doing when he provided this permanent manual of praise.” (McCurley, ibid.).
“I believe that a man can find nothing more glorious than these Psalms; for they embrace the whole life of man, the affections of his mind, and the motions of his soul. To praise and glorify God, he can select a psalm suited to every occasion, and thus will find that they were written for him.”
Athanasius (296–373), Treatise on the Psalms.
“The Book of Psalms is a compendium of all divinity; a common store of medicine for the soul; a universal magazine of good doctrines profitable to everyone in all conditions.”
Basil of Caesarea (c. 379).
“Now what Saint Augustine says is true, that no one is able to sing things worthy of God unless he has received them from Him. Wherefore, when we have looked thoroughly everywhere and searched high and low, we shall find no better songs nor more appropriate to the purpose than the Psalms of David which the Holy Spirit made and spoke through him. And furthermore, when we sing them, we are certain that God puts the words in our mouths, as if He Himself were singing in us to exalt His glory.”
John Calvin, Epistle to the Reader, Genevan Psalter (1542).
The Westminster Assembly recognized that the singing of psalms is an element of worship and evidently believed that commissioning a metrical translation of the Book of Psalms was sufficient to supply to the church for engaging in this duty. (See Westminster and Worship Examined in The Confessional Presbyterian Journal (2008) for proof that the confession is Exclusive Psalmody).
G.I. Williamson persuasively addresses the sufficiency of the Psalter:
“Let us suppose, for a moment, that the Old Testament book of Psalms was not adequate as the vehicle of praise for the New Testament church. Is it not self-evident that, if this really was the case, the first to realize it would have been our Lord? Our Lord did realize that there was need for a new sacrament. That is why He instituted the sacrament of His body and blood that we call the Lord’s Supper. Yet on the very occasion that He did this He led His disciples in the singing of a psalm out of the Psalter. And, according to all the evidence that I have seen, the apostle Paul followed his Lord’s example. He did not, himself, write new songs. What he did was to instruct both the Ephesians and the Colossians to sing the pneumatic [spiritual] psalms, hymns, and songs that they already had—something they could easily do because they had the Psalter in their Septuagint version of the Bible. The apostles were inspired men. If there had been a deficiency in the book of Psalms, which they inherited in the Old Testament Scriptures, then they would surely have been quick to realize it. And, realizing it, they certainly could have done something to remedy the deficiency. They could even have given us a book of inspired New Testament songs. But they did not do so. So the argument that new eras of redemptive revelation always bring forth new songs of praise is simply contrary to historical fact.
“ Much present day argumentation for uninspired songs is based on the presumption that the Psalter is deficient as the song book of the church of the new covenant. Very different was the view of Calvin, who wrote:
“I have been accustomed to call this book I think not inappropriately, ‘An Anatomy of all the Parts of the Soul’…In short, as calling upon God is one of the principal means of securing our safety, and as a better and more unerring rule for guiding us in this exercise cannot be found elsewhere than in The Psalms, it follows, that in proportion to the proficiency which a man shall have attained in understanding them, will be his knowledge of the most important part of celestial doctrine….It is by perusing these inspired compositions, that men will be most effectually awakened to a sense of their maladies, and, at the same time, instructed in seeking remedies for their cure…There is no other book in which there to be found more express and magnificent commendations, both of the unparalleled liberality of God towards his Church, and of all his works; there is no other book in which there is recorded so many deliverances, nor one in which the evidences and experiences of the fatherly providence and solicitude which God exercises towards us, are celebrated with such splendour of diction, and yet with the strictest adherence to truth; in short there is no other book in which we are more perfectly taught the right manner of praising God, or in which we are more powerfully stirred up to the performance of this religious exercise….here there is nothing wanting which relates to the knowledge of eternal salvation.” (Calvin’s Preface to his Commentaries on the Psalms, pp. xxxviii & xxxix)
“…after we have sought on every side, searching here and there, we shall find no songs better and more suitable for our purpose than the Psalms of David, dictated to him and made for him by the Holy Spirit.” (Opera, Vol. VI, pp. 171-172)
The Scottish Reformer, John Knox, echoes the same sentiment: “…there are no songs more meet than the Psalms of the prophet David, which the holy Ghost has framed to the same use, and commended to the Church as containing the effect of the whole Scriptures, that thereby our hearts might be more lively touched…” (John Knox works, Vol. 4, pp. 164-166).”
G.I. Williamson, The Regulative Principle of Worship, Ordained Servant, vol. 10, No. 4, p. 74.
Anglican clergyman William Romain questions those who would propose that human composed hymns are superior to the Psalms:
“I want a name for that man who should pretend that he could make better hymns than the Holy Ghost. His collection is large enough; it wants no addition. It is as perfect as its Author, and not capable of any improvement. Why, in such a case, would any man in the world take it into his head to sit down and write hymns for the use of the Church? It is just the same as if he were to write a new Bible, not only better than the old, but so much better that the old may be thrown aside. What a blasphemous attempt! And yet our hymn-mongers, inadvertently I hope, have come very near to this blasphemy; for they shut out the Psalms, introduce their own verses into the Church, sing them with great delight, and, as they fancy with great profit; although the practice be in direct opposition to the command of God, and, therefore, cannot possibly be accompanied with the blessing of God.”
(William Romaine, Works, An Essay on Psalmody, p. 996).
Objection: You can’t sing the name of Jesus if you only sing the Psalms.
Answer: This argument may seem emotionally persuasive, but it is rooted in ignorance. There are many reasons why this objection is inadequate, it is beyond the scope of this article to address them all. Please read “Do We Sing Jesus Christ’s Name in the Psalter?” by Rev. Travis Fentiman.
Objection: The Bible says to sing hymns and spiritual songs too, not just the Psalms.
Answer: “Psalms, hymns, and spiritual songs does not mean the Psalms of David, the hymns of Fanny Crosby, and the modern day charismatic choruses. That’s eisegesis.” (McCurley, ibid.). What does the Bible mean by that phrase? Our interpretation must be consistent with what we’ve learned above, even if other interpretations are exegetically possible, because Scripture does not contradict itself. The best explanation is that it is a reference to the Book of Psalms. See here: Psalms, Hymns, and Spiritual Songs.
In conclusion, we’ve seen that the case for Exclusive Psalmody is made by demonstrating that the Bible commands the singing of Psalms in worship and simply not finding a command to sing anything else. The Bible does not need to explicitly say “sing Psalms exclusively” it just has to prescribe Psalm singing and not prescribe anything else.
We found that the pattern of Scripture, from beginning to end, is that worship songs were always composed by the inspiration of the Holy Spirit, either for temporary and special occasions, or for perpetual use in public and private worship. And that a canonical book of praise songs was compiled by the Holy Spirit to supply the material needed to fulfill the commands for sung praise throughout the history of the Church. Lastly, we saw that this canonical book of praise is sufficient for New Testament worship, and if it was not, then our Beloved Lord and Savior would have continued the prophetic offices and gifts required for the composing of worship songs throughout the ages or simply added to the Book of Psalms before the close of the entire canon of Scripture upon the completion of the New Testament.
Let us receive God’s Word with joy and approach him in worship on his own terms, rather than with the work of men’s hands!
 Samuel Rutherford, The Divine Right of Church Government, p. 119.
 “Until the final collection and close of the Psalter along with the rest of the Old Testament canon, probably during the time of Ezra and Nehemiah, the question of the exclusive use of any book of songs is out of place. The Psalter was not closed until the Old Testament canon was closed. To raise the existence of these songs as an objection to exclusive psalmody makes about as much or as little sense as appealing to passages like 1 Corinthians 5:9 and Colossians 4:16 for the authority to preach from non-canonical materials. We freely grant that some songs were sung in Old Testament worship which were not finally included in the Psalter, just as we grant that Paul wrote some letters which functioned authoritatively in the Church but which were not finally included in the canon of Scripture as we now have it.” (Michael Bushell, Songs of Zion, p. 189).
c.f. Daniel Kok, Psalmody and Other Songs in Scripture.
 “The “second Song of Moses” (Deuteronomy 32) was not given, even in its original context, as a worship song, but as a song of warning to the children of Israel. It was not given to be “sung to the Lord” but, as stated in Deuteronomy 31:19-22, as a witness of the Lord speaking to His people, against them. It is clear from the Lord’s stated use of this song that it was never intended by Him to be a song “vertically oriented” that is, going up to Him as an offering of the lips (Hebrews 13.15), but a song of witness and warning from Him to His people.” (Rev. Todd Ruddell, Exclusive Psalmody website).
 Brian Schwertley, Exclusive Psalmody: A Biblical Defense.
See also: Song in the Public Worship of God by John Murray
Exclusive Psalmody – Traditional or Scriptural? by Rev. Gavin Beers