7:153Al-A'raaf

Whatever you assert and whatever you call to is indeed good. But if you inform us that there is atonement of our past deeds (then we would embrace Islam). Then it was revealed: And those who call not unto another god along with Allah and slay not any soul which Allah has forbidden except in the cause of justice, nor commit fornication; and he who does this shall meet the requital of sin. Multiplied for him shall be the torment on the Day of Resurrection, and he shall therein abide disgraced, except him who repents a believes and does good deeds. Then these! for the Allah shall change their vices into virtues. Verily Allah is Ever Forgiving, Merciful (xxv. 68-70). Say thou: O my bondsmen woo have committed extravagance against themselves despair not of the Mercy of Allah I Verily Allah will forgive the sins altogether. He is indeed the Forgiving, the Merciful (xxxix. 53).

Some people used to kill, and they did a great deal of it, and they used to commit adultery and they did a great deal of it, and they committed violations. They came to the Prophet and said: "O Muhammad, what you say and call people to is good, if only you could tell us that there is any expiation for what we have done." Then Allah, the Mighty and Sublime, revealed: "And those who invoke not any other ilah (god) along with Allah up to for those, Allah will change their sins into good deeds," he said: "So Allah will change their Shirk into faith, and their adultery into chastity. And the Verse: "Say: O 'Ibadi (My slaves) who have transgressed against themselves (by committing evil deeds and sins)" was revealed.

"A man from among the Ansar accepted Islam, then he apostatized and went back to Shirk. Then he regretted that, and sent word to his people (saying): 'Ask the Messenger of Allah and said: 'So and so regrets (what he did), and he has told us to ask you if there is any repentance for him?' Then the Verses: 'How shall Allah guide a people who disbelieved after their Belief up to His saying: Verily, Allah is Oft-Forgiving, Most Merciful' was revealed. So he sent word to him, and he accepted Islam."

“If you were to commit sin until your sins reach the heaven, then you were to repent, your repentance would be accepted.”