It is narrated from Sayyiduna Ali (may Allah be pleased with him) that once a Bedouin came to the service of the Prophet (peace and blessings be upon him) and asked: "O Messenger of Allah! We live in the countryside, tell us, if any of us passes wind, what should he do?" The Prophet (peace and blessings be upon him) said: "Allah is not shy of the truth (therefore I say to you without hesitation that in such a case) he should perform ablution. And remember! Do not have intercourse with a woman in her anus."
Hadith Referenceمسند احمد / مسند الخلفاء الراشدين / 655
Hadith Gradingحکم دارالسلام:إسناده ضعيف لضعف مسلم بن سلام، والقطعة الأخيرة : لا تأتوا النساء فى أدبارهن صحيحة بشواهدها