Musnad Ahmad 32:472

Hashim ibn al-Qasim narrated to us, Sulayman narrated to us, from Thabit, who said: I said to Anas, "O Abu Hamzah, narrate to us something of these wonders that you witnessed, not narrating it from anyone else." He said: The Messenger of Allah (ﷺ) prayed the Dhuhr prayer one day, then he went until he sat on the benches upon which Gabriel used to come to him. Then Bilal came and called him for the Asr prayer. Everyone who had family in Medina stood up to relieve themselves and perform ablution. There remained men from the Emigrants (Muhajirun) who had no families in Medina. A vessel containing water was brought to the Messenger of Allah (ﷺ), and the Messenger of Allah (ﷺ) placed his palm into the vessel. The vessel could not contain the entire palm of the Messenger of Allah (ﷺ), so he placed these four fingers into the vessel. Then he said, "Approach and perform ablution," while his hand was in the vessel. So they performed ablution until not one of them remained except that he had performed ablution. I said, "O Abu Hamzah, how many do you estimate they were?" He said, "Between seventy and eighty."