Sunan Abi Dawud 246

"Can you show me how the Messenger of Allah used to perform ablution?" 'Abdullah bin Zaid said: "Yes," So he called for water, poured it over his hands and washed his hands twice. Then he raised his mouth and sniffed water up into his nostrils three times. Then he washed his face three times and his arms up to his elbows twice. Then he wiped his head with his hands, from front to back. He started at the front of his head, then went with them to the nape of his neck, then he brought them back, returning them to the place he started, then he washed his feet."

When Ibn 'Abbas (رضي الله عنه) did ghusl in the case of janabah, he would scoop water with his right hand onto his left and wash it seven times before putting it into the vessel. On one occasion he forgot how many times he had scooped water unto his hand, so he asked me (Shu'bah). How many times did I scoop water? I said: I do not know. He said: May you be bereft of your mother! Why don't you know? Then he did wudoo' as for prayer, then he poured water over his head and body. He said: This is how the Messenger of Allah (ﷺ) used to purify himself, i.e., do ghusl.

Shu'ba said that when Ibn ‘Abbas washed because of seminal defilement he emptied water seven times from his right hand over his left hand, then washed his private parts. Once he forgot how often he had emptied it, so he asked Shu'ba, but he replied that he did not know, so he said, “You should be ashamed of yourself. What prevents you from knowing?” Then he would perform his ablution for prayer, then pour water over his body and say, “Thus was God’s messenger accustomed to purify himself.” Abu Dawud transmitted it.