A Penitential Psalm - Psalm 51 is one of the psalms traditionally read and sung during the Lenten season. My version is SATB, and is split into two parts - the opening section, asking for mercy for sins, then a quiet section, thanking God for truth and peace.

Psalm 51, part I

HAVE mercy have on me, O God, according to thy great mercy.
And according to the multitude of thy tender mercies blot out my iniquity.,
Wash me yet more from my iniquity, and cleanse me from my sin.
For I know my iniquity, and my sin is always before me.

Part II

For behold thou hast loved truth.
Thou shalt sprinkle me with hyssop.
Thou shalt wash me.
Thou shalt give joy and gladness.
Thou wilt open my lips,
and my mouth shall declare thy praise.

Turn away thy face from my sins
Create a clean heart in me, O God.
Restore unto me the joy of thy salvation, and strengthen me with a perfect spirit.
Amen.