It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that a man from the Ansar accepted Islam, then he apostatized and joined the polytheists. Then he felt remorse and sent a message to his people to ask the Messenger of Allah (peace and blessings be upon him): Is there any way of repentance for me? Then these verses were revealed, from "How shall Allah guide a people who disbelieved after their belief and had witnessed that the Messenger is true and clear proofs had come to them" to "except those who repent after that and make amends; for indeed Allah is Forgiving, Merciful" [Surah Al Imran: 86 - 89] . The narrator said: The people of his tribe came to him, and he accepted Islam again. This hadith has a sahih (authentic) chain of narration, but the two Shaykhs (Bukhari and Muslim) did not record it.