يَا أَيُّهَا الَّذِينَ آمَنُوا لَا تَدْخُلُوا بُيُوتًا غَيْرَ بُيُوتِكُمْ حَتَّى تَسْتَأْنِسُوا وَتُسَلِّمُوا عَلَى أَهْلِهَا ذَلِكُمْ خَيْرٌ لَكُمْ لَعَلَّكُمْ تَذَكَّرُونَ ﴿۲۷﴾ فَإِنْ لَمْ تَجِدُوا فِيهَا أَحَدًا فَلَا تَدْخُلُوهَا حَتَّى يُؤْذَنَ لَكُمْ وَإِنْ قِيلَ لَكُمُ ارْجِعُوا فَارْجِعُوا هُوَ أَزْكَى لَكُمْ وَاللَّهُ بِمَا تَعْمَلُونَ عَلِيمٌ ﴿۲۸﴾

﴾27﴿ Yaaa aiyuhal lazeena aamanoo laa tadkhuloo buyootan ghaira buyootikum hatta tastaanisoo wa tusallimoo 'alaa ahlihaa; zaalikum khairul lakum la'allakum tazakkaroon
﴾28﴿ Fa il lam tajidoo feehaaa ahadan falaa tadkhuloohaa hattaa yu'zana lakum wa in qeela lakumurji'oo farji'oo huwa azkaa lakum; wallaahu bimaa ta'maloona 'Aleem

﴾27﴿ O people of faith, do not enter houses other than your own until you make yourself known and seek permission, and greet the inhabitants of those houses. This is better for you so that you may take heed of this command
﴾28﴿ So if you do not find anyone in the house (to grant permission), do not enter it until permission is given to you. And if you are told to go back, then turn back; this is purer for you and will save you from disgrace. And Allah, the Exalted, knows well about your deeds

[27] From this verse up to (35) is the third chapter, in which ten etiquettes are mentioned—these are means to prevent indecency, and at the end, there is encouragement.
In this verse, the first etiquette is mentioned: entering each other’s homes.
That is, entering someone’s residence requires permission.
Entering without permission is forbidden, and a major harm in this is that if someone enters suddenly without permission, it might happen that a man or woman in the house is in a state of undress, exposing their private parts.
This is immodesty.
Therefore, this ruling applies not only to the wife's residence but to every home and place of residence—even the mother’s residence is included in this ruling.
Similar to this is mentioned in the hadith of Ibn Jarir al-Tabari and others.
(“حَتَّى تَسْتَأْنِسُوا”)—The meaning of isti'nās is to seek permission.
However, since there are no specific words prescribed for seeking permission, the purpose is simply the customary polite request used by people of the house.
That’s why the word isti'nās is used.
There are several ways to do this:
1. The first method is to stand to the side of the door and call out: "I am so-and-so, I seek permission to enter," and to combine this with the greeting of peace (salām).
2. The second method is to send someone to call the person being sought.
When the person comes with the messenger, then no further permission is required—the coming with the messenger is considered as permission.
3. The third method is to knock gently and wait for permission to be granted.
All three of these methods are mentioned in authentic hadiths.
4. The fourth method, mentioned in the hadith of Ibn Mājah, is that isti'nās can also be to say phrases like “Subḥān Allāh,” “Allāhu Akbar,” or “Al-ḥamdu lillāh,” or to clear the throat, in such a way that the people of the house become aware of someone’s presence and then wait for their permission.
(“وَتُسَلِّمُوا عَلَى أَهْلِهَا”)—The meaning of giving salām here is to say “As-salāmu ‘alaykum, may I enter?” at the time of requesting permission.
This greeting should be said three times.
Or, the meaning could be that salām is given at the time of entering after permission is granted.
According to a narration from Abū Hurayrah (may Allah be pleased with him), if someone enters with permission but does not offer salām, they should be sent back until they give salām.
Note: Seeking permission is so obligatory that if someone looks into another person’s house before asking for permission, the people of the house are allowed to strike his eye with a stick and blind it.
This is mentioned in an authentic hadith in Sahih Muslim, and it is to be understood according to its apparent meaning.
[28] The purpose of the verse is that entering without permission is prohibited.
If the owner of the house is not present, or is present but does not grant permission and remains silent, then one must not enter.
And if one is told to return, then returning is obligatory, and there is no need to be upset about it.