John of Damascus

So from all these and many other examples beyond count we learn the virtue of tears and repentance. Only the manner thereof must be noted—it must arise from a heart that hates sin and weeps, as the prophet David says.… Again the cleansing of sins will be wrought by the blood of Christ, in the greatness of his compassion and the multitude of the mercies of that God who says, "Though your sins be as scarlet, I will make them white as snow."