(17) باب تَحْرِيمِ النَّظَرِ إِلَى الْعَوْرَاتِ
'Abd al-Rahman, the son of Abu Sa'id al-Khudri, reported from his father:
The Messenger of Allah (ﷺ) said: A man should not see the private parts of another man, and a woman should not see the private parts of another woman, and a man should not lie with another man under one covering, and a woman should not lie with another woman under one covering.
Reference: Sahih Muslim 338 a
In-book reference: Book 3, Hadith 90
USC-MSA web (English) reference(deprecated numbering scheme): Book 3, Hadith 667