Psalms 51:19 - Matthew Poole's English Annotations on the Holy Bible

Then; when thou hast granted my humble requests expressed in the former verses, when thou hast renewed, and pardoned, and comforted me, and restored thy favour unto thy people and this city. The sacrifices; which now for our sins thou mayst justly reject and abhor. Of righteousness; which I and my people, being justified and reconciled to thee, shall offer with sincere and penitent hearts. These are opposed to the sacrifices of the wicked, which God abhors, Proverbs 15:8 Isaiah 1:11, &c. Then shall they offer, i.e. they who by thy appointment are to do that work, the priests in the name and on the behalf of thy people. Bullocks; the best and costliest sacrifices, and that in great numbers, in testimony of their gratitude to God, for thy great favour in pardoning mine and their sins, and preventing that total ruin which we had reason to expect and fear upon that account.