Musnad Ahmad 32:799

Muhammad ibn Ja‘far narrated to us, Sa‘id narrated to us, dictating from Qatadah, from Anas ibn Malik: "The Prophet of Allah (peace and blessings of Allah be upon him) was at al-Zawra’, and a vessel containing water was brought to him that did not cover his fingers, or [it was] the amount that would cover his fingers. He ordered his companions to perform ablution. He placed his palm into the water, and the water began to spring forth from between his fingers and the tips of his fingers, until the people performed ablution." He [the narrator] said: We said to Anas, "How many were you?" He said, "We were three hundred."