King David wrote this (under the inspiration of the H.S.) after he was confronted about murdering Uriah and committing adultery with Uriah's wife Bathsheba:
Have mercy on me, O God,
according to your unfailing love;
according to your great compassion
blot out my transgressions.
2 Wash away all my iniquity
and cleanse me from my sin.
3 For I know my transgressions,
and my sin is always before me.
4 Against you, you only, have I sinned
and done what is evil in your sight;
5 Surely I was sinful at birth,
sinful from the time my mother conceived me.
7 Cleanse me with hyssop, and I will be clean;
wash me, and I will be whiter than snow.
10 Create in me a pure heart, O God,
and renew a steadfast spirit within me.
11 Do not cast me from your presence
or take your Holy Spirit from me.
12 Restore to me the joy of your salvation
and grant me a willing spirit, to sustain me.
15 Open my lips, Lord,
and my mouth will declare your praise.
16 You do not delight in sacrifice, or I would bring it;
you do not take pleasure in burnt offerings.
17 My sacrifice, O God, is
[b] a broken spirit;
a broken and contrite heart
you, God, will not despise.