Musnad Ahmad 1166:1

'Abd al-Razzaq narrated to us, he said: Ma'mar narrated to us, from Ibn Tawus, from al-Muttalib ibn 'Abd Allah ibn Hantab, from Umm Hani', she said: "The Messenger of Allah (peace and blessings of Allah be upon him) descended on the day of the Conquest at the highest part of Makkah." I came to him, and Abu Dharr brought a large bowl containing water. She said: "I could see the traces of dough in it." She said: "He—meaning Abu Dharr—screened him, and he performed ghusl. Then the Prophet (peace and blessings of Allah be upon him) prayed eight rak'ahs," and that was during the forenoon (Duha).