Have mercy on me, O God,
according to your unfailing love;
according to your great compassion
blot out my transgressions.
Wash away all my iniquity
and cleanse me from my sin.
Wash me, and I will be whiter than snow.
Let me hear joy and gladness;
let the bones you have crushed rejoice.
Hide your face from my sins
and blot out all my iniquity.
Create in me a pure heart, O God,
and renew a steadfast spirit within me.
Do not cast me from your presence
or take your Holy Spirit from me.
Restore to me the joy of your salvation
and grant me a willing spirit, to sustain me.
Taken from Psalm 51.