The Prophet ﷺ said: A man should not look at the private parts of another man, and a woman should not look at the private parts of another woman. A man should not lie with another man without wearing lower garment under one cover; and a woman should not be lie with another woman without wearing lower garment under one cover. (Using translation from Abū Dāʾūd 4018)
قَالَ النَّبِيُّ ﷺ «لَا يَنْظُرِ الرَّجُلُ إِلَى عَوْرَةِ الرَّجُلِ وَلَا تَنْظُرِ الْمَرْأَةُ إِلَى عَوْرَةِ الْمَرْأَةِ وَلَا يُفْضِي الرَّجُلُ إِلَى الرَّجُلِ وَلَا تُفْضِي الْمَرْأَةُ إِلَى الْمَرْأَةِ»