Musnad Ahmad 3:57

Zakariya ibn 'Adi narrated to us, 'Ali ibn Mushir narrated to us, from Hisham ibn 'Urwah, from his father, from Marwan—and I do not think he is accused by us—who said: 'Uthman was afflicted with a nosebleed in the year of the nosebleed, to the point that he stayed behind from the Hajj and made his will. A man from Quraysh entered upon him and said: "Appoint a successor." He said: "Did they say that?" He said: "Yes." He said: "Who is he?" He said: Then he remained silent. He said: Then another man entered upon him and said to him the same as what the first had said to him, and he replied to him in a similar manner. He said: Then 'Uthman said: "Did they say: Al-Zubayr?" He said: "Yes." He said: "As for the One in Whose hand is my soul, if he were the best of them, as far as I know, and the most beloved of them to the Messenger of Allah, may Allah bless him and grant him peace."