Jami` at-Tirmidhi 1164

Ali bin Talq narrated that A Bedouin came to the Prophet and said:“O Messenger of Allah! A man among us would be in the desert and a small smell would come from him, (what should he do) while the water is scarce? So the Messenger of Allah said: “When one of you breaks wind then let him perform Wudu, and do not go into your women in their behinds for indeed Allah is not shy of the truth.”