Musnad Ahmad 30:681

Ibrahim ibn Khalid narrated to us, Rabah narrated to us, from Ma'mar, from al-Zuhri, 'Ubayd Allah ibn 'Abd Allah ibn 'Utbah informed me, that Abu Hurayrah said: A Bedouin stood up and urinated in the mosque, so the people grabbed him. The Messenger of Allah (peace and blessings of Allah be upon him) said to them: "Leave him, and pour a bucket of water, or a pail of water, over his urine. For you were only sent to make things easy, and you were not sent to make things difficult."