Repentance

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: "The Quraysh said to the Prophet (peace and blessings be upon him): 'Supplicate to your Lord for us that He turn Mount Safa into gold for us; if it becomes gold, we will follow you.' The Prophet (peace and blessings be upon him) supplicated to his Lord. Sayyiduna Jibril (peace be upon him) came to him and said: 'Your Lord conveys His salam to you and says to you: If you wish, Mount Safa will become gold for them, but after that whoever among them disbelieves, I will punish him with a punishment that I will not have inflicted on anyone among all the worlds; and if you wish, I will open for them the door of repentance and mercy.' The Prophet (peace and blessings be upon him) said: 'The door of repentance and mercy (is what I choose).'"
Al-Tabarani recorded it, and its narrators are the narrators of the Sahih.

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: In the blessed time of the Prophet (peace and blessings be upon him), we kept reciting this verse for some years: "And those who do not invoke another deity along with Allah Almighty, and do not kill the soul which Allah Almighty has made sacred, except by right, and do not commit adultery." Then this verse was revealed: "Except the one who repents and believes." The narrator says: I never saw the Prophet (peace and blessings be upon him) so happy about anything as he was at the revelation of this verse and at (the revelation of the following verse): "Indeed, We have granted you a clear victory."
Al-Tabarani recorded it in al-Mu'jam al-Awsat, and its chain is hasan (good).