The words of Allah the Exalted: "Say: O My servants who have transgressed against themselves, do not despair of the mercy of Allah"

Sayyiduna Thawban (may Allah be pleased with him), the freed slave of the Prophet (peace and blessings be upon him), narrates: The Prophet (peace and blessings be upon him) said: "I would not love to have the world and everything in it in exchange for this verse: (Allah Almighty says:) 'O My servants who have wronged themselves! Do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, He is the Forgiving, the Merciful.'" A man said: "And whoever commits shirk?" The Prophet (peace and blessings be upon him) said: "Except the one who commits shirk; his case is different."
Al-Tabarani recorded it in al-Mu'jam al-Awsat, and Ahmad recorded something similar, in which he narrated these words: "Except the one who commits shirk; his case is different", and the Prophet (peace and blessings be upon him) said this three times. Its chain contains Ibn Lahi'ah, in whom there is weakness, and his hadith is hasan (good).

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: The Prophet (peace and blessings be upon him) sent a message to Wahshi bin Harb (may Allah be pleased with him), inviting him to Islam. He is the one who had martyred Sayyiduna Hamzah (may Allah be pleased with him). Wahshi sent a message to the Prophet (peace and blessings be upon him): "O Muhammad (peace and blessings be upon him)! How can you invite me, when your claim is that whoever kills, or commits shirk, or commits fornication, incurs sin, and his punishment will be doubled on the Day of Resurrection, and he will abide in it in humiliation? And I have done these things. So do you find any concession for me?" Then this verse was revealed concerning it: "Except the one who repents, believes and does righteous deeds; for them Allah Almighty will replace their evil deeds with good deeds, and Allah Almighty is Forgiving, Merciful." Wahshi said: "O Muhammad (peace and blessings be upon him)! This is a hard condition, that the case of the one who repents, believes and does righteous deeds is different. Perhaps I will not be able to do this." Then Allah Almighty revealed this verse concerning it: "Indeed, Allah Almighty does not forgive that partners be associated with Him, and He forgives whatever is less than that for whomever He wills." Wahshi said: "O Muhammad (peace and blessings be upon him)! I see that this too depends on the will of Allah, so how do I know whether He will forgive me or not? Can there be something other than this?" Then Allah Almighty revealed this verse: "O My servants who have wronged themselves! Do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, He is the Forgiving, the Merciful." Wahshi said: "This is right." Then he accepted Islam. The people said: "O Messenger of Allah! We too have committed the same kind of deeds that Wahshi committed." The Prophet (peace and blessings be upon him) said: "This ruling is general for the Muslims."
Al-Tabarani recorded it in al-Mu'jam al-Awsat; its chain contains Abyan bin Sufyan, whom al-Dhahabi declared da'if (weak).

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates: We used to think that there would be no room for repentance for a person who fell into trial, that is, when he had abandoned his religion after accepting Islam and after coming to know it. Then Allah Almighty revealed this verse concerning those people: "O My servants who have wronged themselves! Do not despair of the mercy of Allah." After this, the narrator mentioned the full hadith, which has already passed in the chapter on the military expeditions and the Hijrah. Its chain contains Ibn Ishaq, who is thiqah (trustworthy) but a mudallis. (Allamah Haythami says:) I say: The hadith narrated by Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) is in Surah al-Talaq.