Mishkat al-Masabih 7:136

‘Abdallah b. Mas'ud reported God’s messenger as saying, “He who repents of a sin is like him who has committed no sin.” In Majah and Baihaqi, in Shu'ab al-iman , transmitted it, the latter saying its only transmitter was an-Nahrani who is unknown. In Sharh as-sunna a tradition traced no farther back than him is transmitted in which he said, “ Nadam is repentance, and he who repents is like him who has committed no sin.”