Musnad Ahmad 32:2137

Bahz narrated to us, Hammam narrated to us, from Qatadah, from Anas, that the Prophet, peace and blessings of Allah be upon him, was [present] at the time of the sun's decline, and his companions were in need of performing ablution. He said: "A shallow bowl containing a little water was brought, and the Prophet, peace and blessings of Allah be upon him, placed his palm into it. It began to gush forth from between his fingers until all the people performed ablution." I said: "How many were you?" He said: "Approximately three hundred."