حَدَّثَنَا ابْنُ أَبِي عُمَرَ، حَدَّثَنَا سُفْيَانُ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ لَوْ أَنَّ رَجُلاً اطَّلَعَ عَلَيْكَ بِغَيْرِ إِذْنٍ فَخَذَفْتَهُ بِحَصَاةٍ فَفَقَأْتَ عَيْنَهُ مَا كَانَ عَلَيْكَ مِنْ جُنَاحٍ ‏"‏ ‏.‏

Abu Huraira reported Allah's Messenger (PBUH) as saying: If a person were to cast a glance in your (house) without permission, and you had in your hand a staff and you would have thrust that in his eyes, there is no harm for you. Translation Not Available

Book reference: Sahih Muslim Book 38 Hadith 5371
Web reference: Sahih Muslim Book 25 Hadith 2158 b