Musannaf Ibn Abi Shayba 36:549

Abu Usama narrated to us, from Hisham ibn Urwah, from his father, from Abdullah ibn al-Zubayr, who said: I said to Uthman on the day of the house (al-Dar): "Go out and fight them, for you have with you those whom Allah has granted victory with fewer than them, and by Allah, it is lawful." He said: "He refused, and said: 'Whoever owes me hearing and obedience, let him obey Abdullah ibn al-Zubayr.'" And he (Abdullah ibn al-Zubayr) was in charge of the house on that day, and he was fasting on that day.