| Barnes' Notes on the Bible Sing unto the Lord - This is the same expression which occurs in the song of Moses Exodus 15:21. Isaiah evidently had that in his eye. He hath done excellent things - Things that are exalted (גאות gê'ûth); that are worthy to be celebrated, and had in remembrance; things that are majestic, grand, and wonderful. This is known in all the earth - Or, more properly, 'Let this be known in all the earth.' It is worthy of being celebrated everywhere. It should be sounded abroad through all lands. This expresses the sincere desire of all who are redeemed, and who are made sensible of the goodness and mercy of God the Saviour. The instinctive and the unceasing wish is, that the wonders of the plan of redeeming mercy should be everywhere known among the nations, and that all flesh should see the salvation of our God.
Gill's Exposition of the Entire BibleSing unto the Lord,.... Psalms, hymns, and spiritual songs, vocally and together, as Gospel churches, to the glory of God; or "sing the Lord" (u), let him be the subject matter of the song, as in Isaiah 12:2 sing how great and good he is; sing what he is in himself, and what he is to others: for he hath done excellent things; he hath wrought out an excellent salvation, which excels all others, being of a spiritual nature, complete and everlasting: it is emphatically a great one, in which God is glorified in all his perfections, and which issues in the eternal glory and happiness of his people. He has brought in an excellent righteousness, a righteousness that excels any righteousness of the creature, men or angels; it being the righteousness of God, a perfect, pure, and spotless one, which serves for many, even all his spiritual seed, and is everlasting: he has offered up an excellent sacrifice, a sacrifice that excels all that were offered up under the law; in the matter, which is himself; in the use and efficacy of it, to atone for sin, and take it away; in the continuance of that efficacy, and in its acceptableness unto God: and he has obtained an excellent victory over all his and his people's enemies, sin, Satan, the world, and death, and made them sharers in his conquests; reference seems to be had to Exodus 15:1, this is known in all the earth; that such a salvation is finished; such a righteousness is brought in; that peace, pardon, and atonement, are procured, and all enemies are conquered; for the Gospel publishing all this has been sent into all the world, and will be more fully preached throughout it in the latter day. (u) "canite Jehovam", Cocceius; Sept.
Geneva Study BibleSing unto the LORD; for he hath done excellent things: this is known in all the earth.
Jamieson-Fausset-Brown Bible Commentary5. Sing, &c.-alluding to Ex 15:21.
Matthew Henry's Concise Commentary12:10-16 When the gospel should be publicly preached, the Gentiles would seek Christ Jesus as their Lord and Saviour, and find rest of soul. When God's time is come for the deliverance of his people, mountains of opposition shall become plains before him. God can soon turn gloomy days into glorious ones. And while we expect the Lord to gather his ancient people, and bring them home to his church, also to bring in the fulness of the Gentiles, when all will be united in holy love, let us tread the highway of holiness he has made for his redeemed. Let us wait for the mercy of our Lord Jesus Christ unto eternal life, looking to him to prepare our way through death, that river which separates this world from the eternal world.
Matthew Henry's Whole Bible CommentaryVerses 4-6 This is the second part of this evangelical song, and to the same purport with the former; there believers stir up themselves to praise God, here they invite and encourage one another to do it, and are contriving to spread his praise and draw in others to join with them in it. Observe, I. Who are here called upon to praise God-the inhabitants of Zion and Jerusalem, whom God had in a particular manner protected from Sennacherib's violence, v. 6. Those that have received distinguishing favours from God ought to be most forward and zealous in praising him. The gospel church is Zion. Christ is Zion's King. Those that have a place and a name in the church should lay out themselves to diffuse the knowledge of Christ and to bring many to him. Thou inhabitress of Zion; the word is feminine. Let the weaker sex be strong in the Lord, and out of their mouth praise shall be perfected. II. How they must praise the Lord. 1. By prayer: Call upon his name. As giving thanks for former mercy is a decent way of begging further mercy, so begging further mercy is graciously accepted as a thankful acknowledgment of the mercies we have received. In calling upon God's name we give unto him some of the glory that is due to his name as our powerful and bountiful benefactor. 2. By preaching and writing. We must not only speak to God, but speak to others concerning him, not only call upon his name, but (as the margin reads it) proclaim his name; let others know something more from us than they did before concerning God, and those things whereby he has made himself known. Declare his doings, his counsels (so some read it); the work of redemption is according to the counsel of his will, and in that and other wonderful works that he has done we must take notice of his thoughts which are to us-ward, Ps. 40:5. Declare these among the people, among the heathen, that they may be brought into communion with Israel and the God of Israel. When the apostles preached the gospel to all nations, beginning at Jerusalem, then this scripture was fulfilled, that his doings should be declared among the people and that what he has done should be known in all the earth. 3. By a holy exultation and transport of joy: "Cry out and shout; welcome the gospel to yourselves and publish it to others with huzzas and loud acclamations, as those that shout for victory (Ex. 32:18) or for the coronation of a king," Num. 23:21. III. For what they must praise the Lord. 1. Because he has glorified himself. Remember it yourselves, and make mention of it to others, that his name is exalted, has become more illustrious and more conspicuous; in this every good man rejoices. 2. Because he has magnified his people: He has done excellent things for them, which make them look great and considerable. 3. Because he is, and will be, great among them: Great is the Holy One, for he is glorious in holiness; therefore great, because holy. True goodness is true greatness. He is great as the Holy One of Israel, and in the midst of them, praised by them (Ps. 76:1), manifesting himself among them, and appearing gloriously in their behalf. It is the honour and happiness of Israel that the God who is in covenant with them, and in the midst of them, is infinitely great. | 
