Sahih Muslim Book 31, Hadith Number 5940.

‘Abdullah b. Zubair reported on the Day of the Battle of the Trench: I and Umar b. Abu Salama were with women folk in the fort of Hassan (b. Thabit). He at one time leaned for me and I cast a glance and at another time, I leaned for him and he would see and I recognised my father as he rode on his horse with his arms towards the tribe of Quraizah. ‘Abdullah b. ‘Urwa reported from Abdullah b. Zubair: I made a mention of that to my father, whereupon he said: My son, did you see me (on that occasion)? He said: Yes. Thereupon he said: By Allah, Allah’s Messenger (may peace be upon him) addressed me saying: I would sacrifice for thee my father and my mother.