Musnad Ahmad

It is narrated from Sayyiduna Abu Umamah bin Sahl (may Allah be pleased with him) that during the days when Sayyiduna Uthman (may Allah be pleased with him) was besieged in his house, we were with him. For a short while, he entered a room, and those sitting on the bench could also hear what he was saying. In the same way, once he entered that room, and after a short while, he came out and said, "These people have just now threatened to kill me." We said, "O Leader of the Believers! May Allah suffice you and protect you from them." Sayyiduna Uthman (may Allah be pleased with him) said, "For what crime would these people kill me? When I have heard the Prophet (peace and blessings of Allah be upon him) say that it is not lawful to shed the blood of a Muslim except in one of three cases: a man who becomes an apostate after accepting Islam, or a married person who commits adultery, or a murderer who is killed in retaliation for the one he killed. By Allah! Since Allah has guided me, I have never preferred any other religion over this religion. As for Islam, let alone that, even in the days of ignorance I never committed adultery, nor have I killed anyone. Then why do these people want to kill me?"