Psalm 51:1-4 

1 Have mercy upon me, O God, according to thy lovingkindness: according unto the multitude of thy tender mercies blot out my transgressions.
2 Wash me throughly from mine iniquity, and cleanse me from my sin.
3 For I acknowledge my transgressions: and my sin is ever before me.
4 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.