Abd Khayr (may Allah have mercy on him) says: Sayyiduna Ali (may Allah be pleased with him) came to us; he had already prayed, and then he called for water. We said: What will you do with water when you have already prayed? He wanted to teach us the manner of ablution. So a vessel containing water and a basin were brought. He (may Allah be pleased with him) poured water from the vessel onto his right hand and washed it three times, then rinsed his mouth and sniffed water into his nose three times; he would rinse his mouth and clean his nose with the same palm with which he took the water. Then he washed his face three times and washed his right and left hands three times. Then he put his hand into the vessel and wiped his head once. Then he washed his right and left feet three times, and then said: "Whoever would like to know the ablution of the Messenger of Allah (peace and blessings be upon him), this is his (peace and blessings be upon him) ablution."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 319