Musnad Abu Ya'la al-Mawsili 115:195

Muhammad ibn Mahdi narrated to us, Abd al-Razzaq narrated to us, Ma'mar informed us, from Thabit and Qatadah, from Anas, who said: Some of the companions of the Prophet, may Allah bless him and grant him peace, looked for water for ablution but did not find any. The Prophet, may Allah bless him and grant him peace, said: "Is there any here?" He said: So I saw the Messenger of Allah, may Allah bless him and grant him peace, place his hand in the vessel that contained the water. He said: "Perform ablution in the name of Allah." He said: So I saw the water gushing from between his fingers, and the people were performing ablution until the last of them had performed ablution. Thabit said: I said to Anas, "How many do you think they were?" He said: "About seventy men."