Musnad Abu Ya'la al-Mawsili 117:193

Ishaq narrated to us, Hammad narrated to us, from Thabit, who said: I think it is from Anas, that a Bedouin urinated in the mosque. Some of the people jumped up [to stop him]. He said: The Messenger of Allah, may Allah bless him and grant him peace, said: "Do not interrupt him." Then he called for a bucket of water and poured it over it.