﴿ يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لَا تَدْخُلُوا۟ بُيُوتًا غَيْرَ بُيُوتِكُمْ حَتَّىٰ تَسْتَأْنِسُوا۟ وَتُسَلِّمُوا۟ عَلَىٰٓ أَهْلِهَا ۚ ذَٰلِكُمْ خَيْرٌۭ لَّكُمْ لَعَلَّكُمْ تَذَكَّرُونَ ﴾

“O YOU who have attained to faith! Do not enter houses other than your own unless you have obtained permission and greeted their inmates. This is [enjoined upon you] for your own good, so that you might bear [your mutual rights] in mind.”

Allah then prohibited them from entering in on one another without first asking permission, saying: (O ye who believe) in Muhammad (pbuh) and in the Qur'an! (Enter not houses other than your own) you are not permitted to enter houses (without first announcing your presence and invoking peace upon the folk thereof. That) announcing your presence and invoking peace (is better for you) and more akin to righteousness, (that ye may be heedful) that you may take admonition and not enter in on each other without permission.