Musnad Abu Ya'la al-Mawsili 149:144

Abu al-Rabi' narrated to us, Hammad narrated to us, Hisham narrated to us, from his father, from Aisha, that she said: "O Messenger of Allah, all of your wives have kunyas (patronymics) except for me." He said: "Then take a kunya by your nephew, Abdullah ibn al-Zubayr." So she was called Umm Abdullah.