Mukhtasar Bukhari

Narrated Abu Sa'id Al-Khudri (may Allah be pleased with him): I heard the Messenger of Allah (peace and blessings of Allah be upon him) say: When a person becomes a Muslim and his Islam becomes good (excellent and strong), Allah Almighty forgives all the sins he had committed before. After that, the reckoning begins: a good deed is rewarded from ten times up to seven hundred times, and a bad deed is recorded as it is, unless Allah Almighty pardons it.