صحيح مسلم

'A'isha reported that a eunuch used to come to the wives of Allah's Messenger (ﷺ) and they did not And anything objectionable in his visit considering him to be a male without any sexual desire. Allah's Messenger (ﷺ) 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 Messenger (ﷺ) said: I me that he knows these things; do not, therefore. allow him to cater. She (" A'isha) said: Then they began to observe veil from him.