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.
عَنِ النَّبِيِّ ﷺ قَالَ لاَ يَنْظُرُ الرَّجُلُ إِلَى عُرْيَةِ الرَّجُلِ وَلاَ الْمَرْأَةُ إِلَى عُرْيَةِ الْمَرْأَةِ وَلاَ يُفْضِي الرَّجُلُ إِلَى الرَّجُلِ فِي ثَوْبٍ وَاحِدٍ وَلاَ تُفْضِي الْمَرْأَةُ إِلَى الْمَرْأَةِ فِي ثَوْبٍ