Sa'id bin Zayd · The Book of Purification and its Sunnah

The Messenger of Allah performed ablution and he rinsed his mouth three times, and sniffed water up into his nose three times from one handful.

"The Messenger of Allah came to us and asked us for water for ablution. I brought water to him and he rinsed his mouth and sniffed water up into his nostrils from one handful."