Musannaf Ibn Abi Shayba 27:86

Yazid ibn Harun narrated to us, from Humayd al-Tawil, from Anas ibn Malik, who said: The prayer time arrived, so those who were near the mosque stood up and performed ablution, and some people remained. Then a stone vessel containing water was brought to the Messenger of Allah, may Allah bless him and grant him peace. He placed his palm into the vessel, but the vessel was too small for him to spread his palm in it, so he gathered his fingers together, and the people all performed ablution. We said: "How many were they?" He said: "Eighty or more."