Psalms 51:19

Then shalt thou be pleased with the sacrifices of righteousness - “Then,” that is, when God should have thus showed favor to Zion; when he should have poured out his blessing on Jerusalem; when religion should prosper and prevail; when there should be an increase of the pure worship of God. In such offerings as would “then” be made - in sacrifices presented not in mere form, but with sincerity, humility, and penitence - in the outward offering of blood presented with a corresponding sincerity of feeling, and with true contrition, and a proper acknowledgment of the guilt designed to be represen