Qur’an

يَا أَيُّهَا الَّذِينَ آمَنُوا لَا تَدْخُلُوا بُيُوتًا غَيْرَ بُيُوتِكُمْ حَتَّىٰ تَسْتَأْنِسُوا وَتُسَلِّمُوا عَلَىٰ أَهْلِهَا ۚ ذَٰلِكُمْ خَيْرٌ لَّكُمْ لَعَلَّكُمْ تَذَكَّرُونَ ‎

“You who believe! Enter not houses other than your own, until you have asked permission and greeted those in them; that is better for you, in order that you may remember.” (Q24:27)