Muwatta Malik, Book 37, Hadith 5 (USC-MSA) ⓘ

Malik said from Hisham ibn Urwa from his father that an effeminate man was with Umm Salama, the wife of the Prophet, may Allah bless him and grant him peace. He said to Abdullah ibn Abi Umayya while the Messenger of Allah, may Allah bless him and grant him peace, was listening. "Abdullah! If Allah grants you victory over Ta'if tomorrow, I will lead you to the daughter of Ghailan. She has four folds on her front and eight folds on her back." The Messenger of Allah, may Allah bless him and grant him peace, said, "This sort of man should not enter freely with you." (It was customary to allow men with no sexual inclination to enter freely where there were women).

حَدَّثَنِي مَالِكٌ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، أَنَّ مُخَنَّثًا، كَانَ عِنْدَ أُمِّ سَلَمَةَ زَوْجِ النَّبِيِّ صلى الله عليه وسلم ‏.‏ فَقَالَ لِعَبْدِ اللَّهِ بْنِ أَبِي أُمَيَّةَ وَرَسُولُ اللَّهِ صلى الله عليه وسلم يَسْمَعُ يَا عَبْدَ اللَّهِ إِنْ فَتَحَ اللَّهُ عَلَيْكُمُ الطَّائِفَ غَدًا فَأَنَا أَدُلُّكَ عَلَى ابْنَةِ غَيْلاَنَ فَإِنَّهَا تُقْبِلُ بِأَرْبَعٍ وَتُدْبِرُ بِثَمَانٍ ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ لاَ يَدْخُلَنَّ هَؤُلاَءِ عَلَيْكُمْ ‏" ‏ ‏.‏