Musannaf Ibn Abi Shayba 1:2030

Abu Bakr narrated to us, he said: Yazid ibn Harun narrated to us, from Yahya ibn Sa'id, from Anas, that a Bedouin urinated in the mosque. So the Messenger of Allah (may Allah bless him and grant him peace) called for a bucket of water and poured it over his urine.