So The Sage has said, "Heresy begins like a black dot in the heart." This can increase until the heart becomes totally black. Similarly, faith begins like a white dot. As faith increases so does the whiteness. If a person's faith is complete, then his heart becomes totally white. So it is written, "Even though your sins are scarlet, they can become as white as snow" (Isaiah 1.18). (Moznei Tzedek, 81)
We see this in hadith literature, such as the following:
Abu Hurairah narrated: God's Messenger, peace be upon him, said:"When a servant [of God[ commits a sin, a black dot is dotted on his heart. Then if that person gives up that evil deed, begs God to forgive him, and repents, then his heart is cleared; but if he repeats the evil deed, then that covering is increased till his heart is completely covered with it. And this is Ar-Ran that God mentioned [in the Qur'an]," No! but on their hearts is the Ar-Ran which they used to earn" (83:14) (At-Tirmidhi, Vol 5 , Hadith No: 3334)We thus see not only is the hadith sited, but Muhammad is called "The Sage", and a Biblical verse is substituted for the Qur'anic reference in the hadith.