Commentary upon the book of Psalms
1. Sing to Jehovah a new song, sing unto Jehovah, all the earth.2. Sing unto Jehovah, bless his name; show forth his salvation from day to day.3. Declare his glory among the heathen; his wonders among all people.
1 Sing unto Jehovah a new song This commencement shows that, as I have already observed, the Psalmist is exhorting the whole world, and not the Israelites merely, to the exercise of devotion. Nor could this be done, unless the gospel were universally diffused as the means of conveying the knowledge of God. The saying of Paul must necessarily hold true,
"How shall they call upon him in whom they have not believed?" (Romans 10:14.)
The same Apostle proves the calling of the Gentiles, by adducing in testimony of it, "Praise the Lord, ye Gentiles, with his people" — from which it follows, that fellowship in the faith stands connected with the joint celebration of praise, (Romans 15:11.) Besides, the Psalmist requires a new song,  not one which was common, and had formerly been raised. He must therefore refer to some unusual and extraordinary display of the Divine goodness. Thus, when Isaiah speaks of the restoration of the Church, which was wonderful and incredible, he says, "Sing unto the Lord a new song," (Isaiah 42:10.) The Psalmist intimates accordingly, that the time was come when God would erect his kingdom in the world in a manner altogether unlooked for. He intimates still more clearly as he proceeds, that all nations would share in the favor of God. He calls upon them everywhere to show forth his salvation, and, in desiring that they should celebrate it from day to day, would denote that it was not of a fading or evanescent nature, but such as should endure for ever.
3 Declare his glory among the heathen Additional terms are adduced to commend the salvation spoken of. It is called his glory and his wonders; which is equivalent to saying that it was glorious and admirable. By such titles the Psalmist would distinguish it from any deliverances which had formerly been granted, as indeed there can be but one opinion, that when God appeared as Redeemer of all the world, he gave a display of his mercy and of his favor, such as he never vouchsafed before. This salvation it was impossible, as I have said, that the Gentile nations could have celebrated, had they been left without it. The words teach us that we can never be said to have rightly apprehended the redemption wrought out by Christ, unless our minds have been raised to the discovery of something incomparably wonderful about it.
 We meet with a psalm very similar to this, in 1 Chronicles 16, delivered by David to Asaph, to be sung on occasion of the removing of the ark from the house of Obed-edom to Zion. But the ode, as it stands in 1 Chronicles 16, is considerably longer, extending from the 8th verse to the 36^th [1 Chronicles 16:8-36]; and this is only the part of it from the 23rd to the 33rd verse [1 Chronicles 16:23-33]. It has been supposed that this part was extracted from the psalm above mentioned, and, with a few inconsiderable alterations, adapted to the solemnity of the dedication of the second temple. This opinion is founded upon the inscription of the psalm in the Septuagint, Vulgate, Æthiopic, and Arabic versions, which is, "A song of David when the house was built after the captivity." Consequently, strictly speaking, this is not a new song. But it may be called new, from its having been adapted to a new purpose -- from its having been intended to celebrate new mercies conferred upon the Jews, and to lead the mind forward to the glorious era of the coming of the Messiah, and the establishment of his kingdom, which probably was the matter of more general expectation among the chosen people, at the period when the temple was rebuilt, than when the ark was brought to Mount Zion from the house of Obed-edom. It may be observed, that the first verse is not in the original poem, as recorded in the book of Chronicles, but appears to have been added for the new occasion to which this shorter psalm was adapted.