Mukhtasar Muslim

It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that some people from among the polytheists had committed much bloodshed and had committed much adultery while in the state of polytheism. Then they came to the Messenger of Allah (peace and blessings of Allah be upon him) and said, "What you say and the path to which you call is good, but tell us, is it an expiation for our past sins? (If it is an expiation, then we will accept Islam)." Then this verse was revealed: "Those who do not call upon any other god along with Allah, nor kill a soul which Allah has forbidden except by right, nor commit adultery—and whoever does these (i.e., murder, adultery, and polytheism) shall meet a penalty. The punishment will be doubled for him on the Day of Resurrection, and he will abide therein in disgrace forever. Except for those who repent, believe, and do righteous deeds, for them Allah will replace their evil deeds with good, and Allah is Most Merciful, Most Forgiving." (And Allah informed those people that if you accept Islam, all your previous sins from the time of polytheism will be forgiven.) And this verse was revealed: "O My servants who have transgressed against themselves, do not despair of the mercy of Allah..." (the complete verse).