Bukhari Collection: ::Book Number 4:: Hadith # 772
Narrated Anas:A bowl of water was brought to the Prophet while he was at Az-Zawra. He placed his hand in it and the water started flowing among his fingers. All the people performed ablution (with that water). Qatada asked Anas, "How many people were you?" Anas replied, "Three hundred or nearly three-hundred."