Abu Dawud Book 1, Hadith Number 110.

Chapter : A man who puts his hands in the utensil before washing it.

Narated By Shaqiq b. Salamah : I saw ‘Uthman b. ‘Affan (perform ablution). He washed his forearms three times and washed his head thrice. He the said: I saw the Messenger of Allah (PBUH) doing like that.

Abu Dawud said: Another version says: “He performed ablution three times only.”