Al-Kāfi - Volume 5 > Protecting Others’ Privacy Is One’s Own Protection of Privacy
Hadith #2

2- عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ هِشَامِ بْنِ سَالِمٍ عَنْ أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) قَالَ أَمَا يَخْشَى الَّذِينَ يَنْظُرُونَ فِي أَدْبَارِ النِّسَاءِ أَنْ يُبْتَلَوْا بِذَلِكَ فِي نِسَائِهِمْ.

2. Ali ibn Ibrahim has narrated from his father from ibn abu ‘Umayr from Hisham ibn Salim who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘Do you not fear, when looking at women’s behind, for your women being looked in the same way.’”