Have mercy on me, O God,
according to your steadfast love;
according to your abundant mercy
blot out my transgressions.
Wash me thoroughly from my iniquity,
and cleanse me from my sin.
For I know my transgressions,
and my sin is ever before me.....
Purge me with hyssop, and I shall be clean;
wash me, and I shall be whiter than snow....
Hid your face from my sins,
and blot out all my iniquities.
Create in me a clean heart, O God,
and put a new and right spirit within me.
Do not cast me away from your presence,
and do not take your holy spirit from me.
(New Revised Standard Version)
Psalm 51 is notably used in the Ash Wednesday service when we clear the decks, as it were, of all the baggage within us, to make a clean start at the beginning of Lent. The symbol of water and washing is used to "blot out" our transgressions. As Handel's famous anthem says "Wash me throughly from my wickeness" (not "thoroughly" notice). In other words wash me inside and out and make me clean again from all my sin. You might like to listen to a lovely setting of this sung by two women choristers on Utube: https://www.youtube.com/watch?v=knJVqkhUzeQ
The Psalm not only asks God to cleanse us from our sin, inside and out, but also to take away the sin of which we are not aware - those things we often conveniently overlook about ourselves. At the end of the verses above, the psalm asks God to give us a clean heart and not to take His Holy Spirit from us.
These are words we might say regularly, and an anthem we might listen to, often.
Heavenly Father,
we acknowledge our sins
both known and unknown,
and ask Your forgiveness.
Wash us clean from all our transgressions
and create a new heart within us
so that we may learn to do Your will
and grow ever closer to You.
Amen.