Ablutions (Wudu')

Bukhari :: Book 1 :: Volume 4 :: Hadith 219

Narrated Abu Huraira:

A Bedouin stood up and started making water in the mosque. The people caught him but the Prophet ordered them to leave him and to pour a bucket or a tumbler of water over the place where he had passed the urine. The Prophet then said, "You have been sent to make things easy and not to make them difficult."