Have mercy on us, O God, according to Your steadfast love, according to Your abundant mercy blot out our transgressions; wash us thoroughly from our iniquity, cleanse us from our sin. For we are well aware of our transgressions, our sins are constantly in mind. Against You, You alone, we have sinned and done what is evil in Your sight. God, create in us a clean heart, renew a right spirit within us. Restore to us the joy of Your salvation, uphold us with a willing spirit. Lord, open our lips, and our mouths will declare Your praise. Amen.
-from Psalm 51 (ESV)