From Sahih Bukhari (Hadith 197):
Narrated `Abdullah bin Zaid:Once Allah's Messenger (ﷺ) came to us and we brought out water for him in a brass pot. He performed ablution thus: He washed his face thrice, and his forearms to the elbows twice, then passed his wet hands lightly over the head from front to rear and brought them to front again and washed his feet (up to the ankles)
Reference: Bukhari 197