A man peeped into one of the dwelling places of the Prophet. The Prophet got up and aimed a sharp-edged arrow head (or wooden stick) at him to poke him stealthily.  

أَنَّ رَجُلاً اطَّلَعَ فِي بَعْضِ حُجَرِ النَّبِيِّ ﷺ فَقَامَ إِلَيْهِ بِمِشْقَصٍ أَوْ بِمَشَاقِصَ وَجَعَلَ يَخْتِلُهُ لِيَطْعُنَهُ  

A man peeped through a hole in the door of Messenger of Allah ﷺ's house, and at that time, Messenger of Allah ﷺ had a Midri (an iron comb or bar) with which he was rubbing his head. So when Messenger of Allah ﷺ saw him, he said (to him), "If I had been sure that you were looking at me (through the door), I would have poked your eye with this (sharp iron bar)." Messenger of Allah ﷺ added, "The asking for permission to enter has been enjoined so that one may not look unlawfully (at what there is in the house without the permission of its people)."  

أَخْبَرَهُ أَنَّ رَجُلاً اطَّلَعَ فِي جُحْرٍ فِي باب رَسُولِ اللَّهِ ﷺ وَمَعَ رَسُولِ اللَّهِ ﷺ مِدْرًى يَحُكُّ بِهِ رَأْسَهُ فَلَمَّا رَآهُ رَسُولُ اللَّهِ ﷺ قَالَ لَوْ أَعْلَمُ أَنْ تَنْتَظِرَنِي لَطَعَنْتُ بِهِ فِي عَيْنَيْكَ قَالَ رَسُولُ اللَّهِ ﷺ إِنَّمَا جُعِلَ الإِذْنُ مِنْ قِبَلِ الْبَصَرِ  

Abul Qasim said, "If any person peeps at you without your permission and you poke him with a stick and injure his eye, you will not be blamed."  

أَبُو الْقَاسِمِ ﷺ لَوْ أَنَّ امْرَأً اطَّلَعَ عَلَيْكَ بِغَيْرِ إِذْنٍ فَخَذَفْتَهُ بِعَصَاةٍ فَفَقَأْتَ عَيْنَهُ لَمْ يَكُنْ عَلَيْكَ جُنَاحٌ