Musannaf Ibn Abi Shayba 37:550

Abu Usama narrated to us, from Abd al-Malik ibn Abi Sulayman, who said: I heard Abu Layla al-Kindi saying: I saw Uthman look out upon the people while he was besieged. He said: "O people, do not kill me, and ask me to repent. For by Allah, if you kill me, you will never fight together ever, and you will never strive against an enemy ever. You will surely differ until you become like this," and he interlaced his fingers. "O my people, let not your opposition to me cause you to be struck by the like of what struck the people of Nuh, or the people of Hud, or the people of Salih; and the people of Lut are not far from you." He said: And he sent for Abdullah ibn Salam and asked him. He said: "Refrain, refrain, for it is more effective for your argument." Then they entered upon him and killed him.