Miserere mei, Deus: secundum magnam misericordiam tuam.
Have mercy on me, O God, according to thy steadfast love; according to thy abundant mercy blot out my transgressions.
I love the Latin more than the English. It is King David lamenting his own spiritual ruin and subsequent forgiveness by God. The Psalm is popularly known as the Miserere. The issue here is not so much the sin as the mercy.
Image: Thanks for the image!