What has been mentioned about it being disliked to enter women in their behinds Jami` at-Tirmidhi 1166
Arabic hadith text
حَدَّثَنَا قُتَيْبَةُ، وَغَيْرُ، وَاحِدٍ، قَالُوا حَدَّثَنَا وَكِيعٌ، عَنْ عَبْدِ الْمَلِكِ بْنِ مُسْلِمٍ، وَهُوَ ابْنُ سَلاَّمٍ عَنْ أَبِيهِ، عَنْ عَلِيٍّ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِذَا فَسَا أَحَدُكُمْ فَلْيَتَوَضَّأْ وَلاَ تَأْتُوا النِّسَاءَ فِي أَعْجَازِهِنَّ " . قَالَ أَبُو عِيسَى وَعَلِيٌّ هَذَا هُوَ عَلِيُّ بْنُ طَلْقٍ
Translation
Ali narrated that The Messenger of Allah said
“When one of you breaks wind then let him perform Wudu, and do not go into your women through their behinds.”