Musannaf Ibn Abi Shayba 1:2032

Ali bin Mushir narrated to us, from Muhammad bin Amr, from Abu Salamah, from Abu Hurairah, who said: A Bedouin entered the mosque while the Messenger of Allah (may Allah bless him and grant him peace) was in it, and he urinated. So he (the Prophet) ordered a bucket of water, and it was poured over his urine.