Sahih Muslim | Book 26 | Chapter 12

Narrated by Umm Salama
Umm Salama reported that she had a eunuch (as a slave) in her house. Allah's Messenger imay peace be upon him) was once in the house that he (the eunuch) said to the brother of Umm Salama: Abdullahb. Aba Umayya; if Allah grants you victory in Ta'if on the next day, I will show you the daughter of Ghailan for she has four folds (upon her body) on the front side of her stomach and eight folds on the back. Allah's Messenger (may peace be upon him) heard this and he said: Such (people) should not visit you.

Narrated by 'Aisha
'Aisha reported that a eunuch used to come to the wives of Allah's Apostle (may peace be upon him) and they did not And anything objectionable in his visit considering him to be a male without any sexual desire. Allah's Apostle (may peace be upon him) one day came as he was sitting with some of his wives and he was busy in describing the bodily characteristics of a lady and saying: As the comes in front tour folds appear on her front side and as she turns her back eight folds appear on the back side. Thereupon Allah's Apostle (may peace be upon him) said: I me that he knows these things; do not, therefore. allow him to cater. She ('Aisha) said: Then they began to observe veil from him.