Have mercy upon me, O God, according to Thy lovingkindness: according unto the multitude of Thy tender mercies blot out my transgressions.
Wash me throughly from mine iniquity, and cleanse me from my sin.  For I acknowledge my transgressions: and my sin is ever before me.
Against Thee, Thee only, have I sinned, and done this evil in Thy sight: that Thou mightest be justified when Thou speakest, and be clear when Thou judgest.
Behold, I was shapen in iniquity; and in sin did my mother conceive me.
Behold, Thou desirest truth in the inward parts: and in the hidden part Thou shalt make me to know wisdom.  Purge me with hyssop, and I shall be clean: wash me, and I shall be whiter than snow.  Make me to hear joy and gladness; that the bones which Thou hast broken may rejoice.
Hide Thy face from my sins, and blot out all mine iniquities.  Create in me a clean heart, O God; and renew a right spirit within me.  Cast me not away from Thy presence; and take no Thy Holy Spirit from me.  Restore unto me the joy of Thy salvation; and uphold me with Thy free spirit.
Then will I teach transgressors Thy ways; and sinners shall be converted unto Thee.
Deliver me from bloodguiltiness, O God, Thou God of my salvation: and my tongue shall sing aloud of Thy righteousness.
O Lord, open Thou my lips; and my mouth shall shew forth Thy praise.  For Thou desirest not sacrifice; else would I give it: Thou delightest not in burnt offering.  The sacrifices of God are a broken spirit: a broken and a contrite heart, O God, Thou wilt not despise.
Do good in Thy good pleasure unto Zion: build Thou the walls of Jerusalem.  Then shalt Thou be pleased with the sacrifices of righteousness, with burnt offering and whole burnt offering: then shall they offer bullocks upon Thine altar.
Psalm 51:1-19