Sahih Muslim | Book 2 | Hadith Number 558

Narrated by Anas b. Malik
Anas b. Malik narrated that a desert Arab (Bedouin) stood in a corner of the mosque and urinated there. The people (the Companions of the Holy Prophet who were present there)

shouted, but the Messenger of Allah (may peace be upon him) said: Leave him alone. When he had finished, the Messenger of Allah (may peace be upon him) ordered that a bucket (of water) should be brought and poured over it.