Musnad Abu Ya'la al-Mawsili 160:194

Muhammad ibn Bakkar narrated to us, Abu Ma'shar narrated to us, from Sa'id, from Abu Hurayrah, who said: A man came to the Messenger of Allah (peace and blessings of Allah be upon him) and said: "What is the completion of ablution (wudu)?" He said: The Messenger of Allah (peace and blessings of Allah be upon him) remained silent regarding him until the prayer time arrived. He said: Then the Messenger of Allah (peace and blessings of Allah be upon him) called for water. He washed his hands, then he cleared his nose (istanthara) and rinsed his mouth, and washed his face three times, and his hands three times each, and wiped his head, and washed his feet three times each. Then he sprinkled water under his garment and said: "This is the completion of ablution."