Sunan Abu Dawood, Chapter: Purification (Kitab Al-Taharah)

AbulAzhar al-Mughirah ibn Farwah and Yazid ibn AbuMalik reported: Mu'awiyah performed ablution before the people, as he saw the Apostle of Allah (peace_be_upon_him) performed ablution. When he reached the stage of wiping his head, he took a handful of water and poured it with his left hand over the middle of his head so much so that drops of water came down or almost came down. Then he wiped (his head) from its front to its back and from its back to its front.