Musnad Ahmad 329:14

'Uthman ibn 'Umar narrated to us, Malik narrated to us, from 'Amr, from his father, that he heard 'Abdullah ibn Zayd al-Ansari being asked about the ablution (wudu) of the Messenger of Allah (peace and blessings of Allah be upon him). He called for water, washed his hands, rinsed his mouth, and sniffed water into his nose three times. He washed his face three times, and washed his hands twice each time. He wiped his head—'Uthman said: Malik wiped his head, bringing his hands forward and backward—and he washed his feet. He said: "This is how I saw the Messenger of Allah (peace and blessings of Allah be upon him) perform ablution."