عَنْ سَهْلِ بْنِ سَعْدٍ رَضِيَ اللَّهُ عَنْهُ أَنَّ رَجُلًا اطَّلَعَ عَلَى النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ مِنْ سِتْرِ حُجْرَتِهِ وَفِي يَدِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ مِدْرًى فَقَالَ لَوْ أَعْلَمُ أَنَّ هَذَا يَنْظُرُنِي حَتَّى آتِيَهُ لَطَعَنْتُ بِالْمِدْرَى فِي عَيْنِهِ وَهَلْ جُعِلَ الِاسْتِئْذَانُ إِلَّا مِنْ أَجْلِ الْبَصَرِ
Sayyiduna Sahl bin Sa’d Sa’idi (may Allah be pleased with him) narrates that a man looked through the curtain hanging at the chamber of the Prophet (peace and blessings be upon him), and the Prophet had a comb in his hand. The Prophet (peace and blessings be upon him) said: If I had known that he was looking at me, I would have come close and struck his eye with this comb. Permission to enter has been legislated because of the (harm of) looking.