(Annoor) 24 : 27
يَا أَيُّهَا الَّذِينَ آمَنُوا لَا تَدْخُلُوا بُيُوتًا غَيْرَ بُيُوتِكُمْ حَتَّىٰ تَسْتَأْنِسُوا وَتُسَلِّمُوا عَلَىٰ أَهْلِهَا ۚ ذَٰلِكُمْ خَيْرٌ لَكُمْ لَعَلَّكُمْ تَذَكَّرُونَ
Oh you who believed! You don’t enter houses other than your houses till you get permission and you greet their inhabitants; that is best for you so that you may remind with hearts.
The verse teaches about basic morals that the believers should follow while entering other houses. See explanation 17: 32 and 24: 1.