It is narrated from Sayyiduna Abdullah bin al-Zubayr (may Allah be pleased with them both) that he said: On the day of the Battle of the Trench, Umar bin Abi Salamah and I were on a fortress. He would bend down for me and I would watch the fighting, and I would bend down for him and he would watch the fighting. I saw my father (Sayyiduna al-Zubayr) in the salty ground, charging at these people one time and at those another time. When he returned I said: Father! I saw you (fighting). He asked: My son, did you really see me? I said: Yes. He said: Today the Messenger of Allah (peace and blessings be upon him) gathered his parents for me (that is, he said: May my father and mother be ransomed for you). This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim).