Have mercy on me, God, in Your Kindness,
in Your Compassion blot out my offence.
O wash me more and more from my guilt
and cleanse me from my sin.
My offences truly I know them:
my sin is always before me.
Against You, You alone, have I sinned;
what is evil in Your Sight I have done.
A pure heart create for me, O God;
put a steadfast spirit within me.
Do not cast me away from Your Presence,
nor deprive me of Your Holy Spirit.
Give me again the joy of Your Help;
with a spirit of fervour sustain me.
O Lord, open my lips
and my mouth shall declare Your Praise.

Psalm 51 
translation selected for In Conversation with God volume 2 for Ash Wednesday