Silsilat al-Ahadith al-Sahihah

Sayyiduna Abu Dharr (may Allah be pleased with him) says: The Truthful and Trusted (Muhammad, peace and blessings be upon him) narrated to us from his Lord that Allah Almighty said: "I reward a good deed tenfold or even more, and I recompense an evil deed only onefold or I may even forgive it. (O My servant!) If you come to Me with sins nearly as much as the earth, I will grant you forgiveness just as great, provided that you did not associate anyone with Me."

It is narrated from Sayyiduna Abu Hurairah, may Allah be pleased with him, that Muhammad, the Messenger of Allah, peace and blessings be upon him, said: "When any one of you perfects his Islam, then every good deed he does is written for him as tenfold up to seven hundredfold, and every bad deed is written as only one bad deed, (and this continues) until he dies and meets Allah, the Exalted."

Sayyiduna Abu Sa'id Khudri (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings of Allah be upon him) said: "When a person accepts Islam and his Islam becomes good, then whatever good deed he had done, Allah Almighty writes it down (and preserves it), and whatever sin he had committed is erased. Then (after that, from Allah Almighty) the further reward is such that one good deed takes the form of ten to seven hundred times, and as for the matter of a sin, it remains only one, unless Allah Almighty also forgives it."