It is narrated from Sayyidah Umm Hani (may Allah be pleased with her) that on the day of the Conquest of Makkah, the Messenger of Allah (peace and blessings be upon him) stopped at an elevated place. I came to him (peace and blessings be upon him), and Abu Dharr (may Allah be pleased with him) brought a vessel containing water. I saw a trace of dough in it. Then Abu Dharr (may Allah be pleased with him) screened him (peace and blessings be upon him) and he (peace and blessings be upon him) took a ritual bath; then the Messenger of Allah (peace and blessings be upon him) screened Abu Dharr (may Allah be pleased with him), and Abu Dharr (may Allah be pleased with him) took a ritual bath. Then he (peace and blessings be upon him) prayed eight rak'ahs, and this was at the time of the forenoon (duha).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 20