Musnad Ahmad 1153:612

Bahz narrated to us, he said: Shu'bah narrated to us, he said: Sa'd ibn Ibrahim narrated to me, he said: I heard 'Urwah ibn al-Zubayr narrating from 'Aishah: "That the Messenger of Allah, peace and blessings of Allah be upon him, used to pray while I was between him and the Qiblah."