عَنْ أَبِي هُرَيْرَةَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «الْعَجْمَاءُ جَرْحُهَا جُبَارٌ وَالْمَعْدِنُ جُبَارٌ وَالْبِئْرُ جُبَارٌ»

Sahl b. Sa'd said that a man looked through a hole in God’s Messenger’s door when God’s Messenger had a spike with which he was scratching his head, so he said, “If I knew that you were seeing me I would poke it in your eyes, for asking permission has been appointed only on account of what people may see.” (Bukhari and Muslim.)