And the duty of singing praises to God seems to be appointed wholly to excite and express religious affections. No other reason can be assigned why we should express ourselves to God in verse, rather than in prose, and do it with music but only, that such is our nature and frame, that these things have a tendency to move our affections.

It’s a good quote, but I’ll try to be more careful.

I did find these quotes:

Another thing, which properly belongs to a christian education, and which would be unusually popular with them, and which would in several respects have a powerful influence, in promoting the great end in view, of leading them to renounce the coarseness, and filth, and degradation, of savage life, for cleanliness, refinement, and good morals, is teaching them to sing. Music, especially sacred music, has a powerful efficacy to soften the heart into tenderness, to harmonize the affections, and to give the mind a relish for objects of a superior character.
[Jonathan Edwards, “Letter to a letter to Sir William Pepperell,” Nov. 28, 1751. (Jonathan Edwards, Works, v. 1)

As it is the command of God, that all should sing, so all should make conscience of learning to sing, as it is a thing which cannot be decently performed at all without learning. Those, therefore, who neglect to learn to sing, live in sin, as they neglect what is necessary in order to their attending one of the ordinances of God’s worship. Not only should persons make conscience of learning to sing themselves, but parents should conscientiously see to it, that their children are taught this among other things, as their education and instruction belongs to them. [Jonathan Edwards, “C H R I S T I A N C A U T I O N S ;OR,THE NECESSITY OF SELF-EXAMINATION.” Works, v. 2]