From the Body of Practical Divinity by Baptist theologian John Gill (1697-1771):
The manner in which psalms, &c. are to be sung may be next considered. . . .
With grace in the heart,” (Col. 3:16) with the several graces; not one note, but a mixture of notes, makes melody; many voices, yet one sound, make a chorus: so singing must be with various graces; with faith in God, without which it is impossible to please him; and with strong love and affection for him; and also “with reverence and godly fear;” for God is “fearful in praises” נורא reverend in them, to be praised with great fear and reverence of his Majesty. . . .
We should have in view the glory of God; for we are to “sing unto the Lord;” not to ourselves, merely to raise our natural affections, to gain applause from others, by the fineness of our voice, and by observing an exact conformity to the tune; but to the glory of Father, Son, and Spirit, the one God, who condescends to inhabit the praises of Israel.