Musnad Ahmad 612:2

Isma'il ibn Ibrahim narrated to us, Ayyub narrated to us, from Abu Qilabah, who said: When Uthman was killed, speakers stood up in Iliya (Jerusalem). The last of them to stand was a man from the companions of the Prophet, may God bless him and grant him peace, who was called Murrah ibn Ka'b. He said: "Were it not for a hadith I heard from the Messenger of God, may God bless him and grant him peace, I would not have stood up. The Messenger of God, may God bless him and grant him peace, mentioned a tribulation—and I believe he said: 'and he brought it near' (Isma'il was uncertain)—then a man passed by, covered [with a garment]. He said: 'This man and his companions will be upon the truth on that day.' I went and took him by his shoulder, and I turned his face toward the Messenger of God, may God bless him and grant him peace, and said: 'This one?' He said: 'Yes.'" He said: "And behold, it was Uthman."