Abu Dawud Book 1, Hadith Number 122.
Chapter : A man who puts his hands in the utensil before washing it.
Narated By Al-Miqdam b. Ma’dikarib : I saw the Apostle of Allah (PBUH) perform ablution. When he reached the stage of wiping his head, he placed his palms on the front of the head. Then he moved them until he reached the nape. He then returned them to the place from where he had started.