Majma al-Zawaid — Hadith 75

Sayyiduna Salamah bin Nufayl (may Allah be pleased with him) narrates: A young man came and sat in front of the Prophet (peace and blessings be upon him), and he said in a loud voice: "O Messenger of Allah! What is your view about a person who has done every evil, committed every sin, seized whatever came before him, and who is such that if his sins were distributed among all the people of Madinah, they would cover all of them?" The Prophet (peace and blessings be upon him) asked him: "Have you accepted Islam?" (The narrator is in doubt, or perhaps the words are:) "Are you a Muslim?" He said: "As for me, I bear witness that there is no god besides Allah Almighty and that Sayyiduna Muhammad (peace and blessings be upon him) is the Messenger of Allah." The Prophet (peace and blessings be upon him) said: "Go! Your evil deeds have been changed into good deeds." He said: "What about my betrayals and my transgressions?" The Prophet (peace and blessings be upon him) said: "Your betrayals and transgressions too (have been changed into good deeds)." He (peace and blessings be upon him) said this three times. (The narrator says:) The young man turned away, and as he went he was saying: "Allahu akbar, Allahu akbar (Allah is the Greatest, Allah is the Greatest)." The narrator says: I kept hearing him saying the takbir until he disappeared from my sight, (the narrator is in doubt, or perhaps the words are:) became hidden from me.
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains a narrator, Yasin al-Zayyat, who narrates fabricated reports.