Mukhtasar Muslim

Sayyiduna Anas bin Malik (may Allah be pleased with him) said: We were sitting in the mosque with the Messenger of Allah (peace and blessings of Allah be upon him) when a Bedouin came and started urinating while standing. The companions of the Messenger of Allah (peace and blessings of Allah be upon him) called out to him to stop, but the Prophet (peace and blessings of Allah be upon him) said, "Do not interrupt his urination, leave him." So the people left him until he finished urinating. Then the Prophet (peace and blessings of Allah be upon him) called him and said, "Mosques are not for urination or filth. They are built for the remembrance of Allah, for prayer, and for reciting the Qur'an," or he said something similar. Then he ordered a man, who brought a bucket of water and poured it over the spot.