Abu Nahshal al-Aswad said to al-Qasim bin Muhammad (may Allah have mercy on him): I saw a slave-girl of mine with her clothing removed, and it was a moonlit night, so I sat with her as a man sits with his wife. She said: "I am menstruating." I did not have intercourse with her. I have gifted her to my son; may he have intercourse with her? Al-Qasim bin Muhammad (may Allah have mercy on him) forbade him from that.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13922