Allaah – the Most High – said:
يَا أَيُّهَا الَّذِينَ آمَنُوا لَا تَدْخُلُوا بُيُوتًا غَيْرَ بُيُوتِكُمْ حَتَّىٰ تَسْتَأْنِسُوا وَتُسَلِّمُوا عَلَىٰ أَهْلِهَا
[[Meaning: O you who believe! Do not enter houses other than your own, until you have asked permission and greeted their inhabitants.]]
Imaam al-Qurtubee rahimahullaah said in his explanation of the Qur∙aan ‘al-Jaami` li Ahkaamil-Qur∙aan’:
The reason for the revelation of this verse is: that which at-Tabaree and other than him report from `Adee bin Thaabit that a woman from the Ansaar tribe said: ‘O Messenger of Allaah! When I am in my house upon a condition that I do not like anyone to see me upon; neither my father nor my son. So my father comes and enters the place I am in, and until now men from my family enter where I am, while I am in such a state – so what should I do? So the verse was revealed.
And he said: “…so if your mother or your sister were living in the same house as you then they [i.e. the people of knowledge] have said: you should [before entering the place they are in] clear your throat, or stamp your foot so that they are notified and aware of your entering…” “…Because ones mother or sister they could be upon a condition that they dislike that you see them in.
Ibnul-Qaasim said that [Imaam] Maalik rahimahullaah said: ‘And a man should seek permission from his mother and his sister if he wishes to enter the place they are in.’
And `Ataa bin Yasaar reported that a man said to the Prophet sallAllaahu `alaihi wa sallam: ‘Should I seek permission when entering the place where my mother is?’ He said: “Yes.” He [the man] said: ‘But I serve her.’ He said: “Seek permission from her.” So he [the man] consulted him three times. Then he said: “Do you like that you would see her naked?!” He [the man] said: ‘No.’ So he sallAllaahu alaihi wa sallam said: “Then seek permission from her” at-Tabaree mentioned it.
Shaykh Muhammad al-Ameen bin Muhammad al-Mukhtaar ash-Shanqeetee rahimahullaah said in ‘Adwaa al-Bayaan’:
“Know that that which is more apparent, and not befitting that one diverts away from is: that it is binding upon a man that he seeks permission when entering the place where his mother, or his sister, or his sons, or his daughters are; [from those of them] that have reached puberty. Because if he were to enter the place where those aforementioned were – without seeking permission –, then it is possible that his eyes may set upon the `Awrah (parts that should be covered) of those mentioned. And that is something impermissible for him.
And Ibn Hajr rahimahullaah said in explanation of the narration: ‘Verily! The command to seek permission when entering has been enjoined because of the sight, (i.e. that one should not look unlawfully at the state of others).’
“And we take from it that it is legislated to seek permission from everybody – even from those relatives it is forbidden for him to marry; so that the `Awrah (parts that should be covered) is not exposed.
And al-Bukhaaree rahimahullaah reports in ‘al-Adab al-Mufrad’ from a narration of Naafi`: That the children of Ibn `Umar radiyAllaahu `anhumaa if they reached the age of puberty he would separate them. And they would not enter the place where he was except if they sought permission.
And from `Alqamah: that a man came to Ibn Mas`ood and said: ‘Should I seek permission to enter the place where my mother is?’ He said: “[Yes]; for you would not wish to see her in every condition.”
And from Muslim bin Nudhayr that he said: “A man asked Hudhayfah, saying: ‘Should I seek permission when entering the place where my mother is?’ So he said: ‘If you did not seek permission when entering upon her you may see that which you dislike.’”
And from Moosaa bin Talhah [bin `Ubaydillaah] that he said: “I entered with my father to where my mother was. He entered, so I followed him. So he turned and pushed me until I fell back onto my backside. Then he said: ‘Do you enter without seeking permission?!’”
And from `Ataa that he asked Ibn `Abbaas: ‘Should I seek permission to enter the place my sister is in?’ So he said: ‘Yes.’ I said: ‘But they live under my care.’ He said: ‘Would you like to see her naked?!’
And the chains of narration for these reports are authentic.” End of Ibn Hajr’s speech.
So these narrations from these companions strengthen that which we have mentioned from seeking permission when entering the places where those we mentioned are. And this is something also understood from the authentic narration: ‘Verily! The order of taking permission to enter has been enjoined because of the sight, (i.e. that one should not look unlawfully at the state of others)’. So seeing the `Awrah (parts which should be covered) of those mentioned is impermissible as you can see.
And Ibn Katheer rahimahullaah mentions in explanation of this verse:
“And Hushaym said: Ash`ath bin Sawwaar informed us: from Kurudoos, from Ibn Mas`ood that he said: ‘It is upon you to seek permission when entering where your mothers or your sisters are.’
And Ibn Jurayj said: I heard `Ataa bin Abee Rabaah narrating that Ibn `Abbaas radiyAllaahu `anhumaa said: “There are three verses that the people have neglected. Allaah the Most High said: “Indeed, the most honourable of you with Allah are those of you who are most fearful and obedient [to Allaah].” He said: But they [the people] say: ‘Indeed the most noble of you with Allaah are the ones with the biggest houses.’ He said: ‘And the people have totally neglected and forgotten all of mannerisms.’ I said: “Should I seek permission to enter upon my orphan sisters under my care, if they are with me in the same house?” He said: ‘Yes.’ So I repeated it to him again; so that he would allow me, but he refused – saying: ‘Would you like to see her naked?!’ I said: “No.” He said: ‘Then seek permission.’ So I consulted him again. So he said: ‘Do you like that you obey Allaah?!’ I said: ‘Yes.’ He said: ‘Then seek permission.’
Ibn Jurayj said: And Ibn Taawoos informed me that his father said: “There is not I woman I dislike to see her `Awrah (parts that should be covered) more than those whom it is forbidden for me to marry.” He said: ‘And he was strict regarding that.’”
And Ibn Jurayj narrated from az-Zuhree, saying: I heard Huzayl bin Shurahbeel al-Awdee, al-A`maa [saying] that he heard Ibn Mas`ood say: ‘It is upon you to seek permission when entering where your mothers are. End.”
Ash-Shawkaanee rahimahullaah mentions in his explanation of the Qur∙aan ‘Fathul-Qadeer’:
“And Sa`eed bin Mansoor and al-Bukhaaree in ‘al-Adab’ report from a narration of Ibn Mas`ood radiyAllaahu `anhu that he said: ‘It is upon a man to seek permission when entering where his father, or his mother, or his brother, or his sister is.’” And Ibn Abee Shaybah and al-Bukhaaree reported the like of that from a narration of Jaabir.
And in the Kuwaiti Fiqh Encyclopaedia it states:
“And if there are any of those whom it is forbidden for him to marry in his house – such as his mother, or his sister, or the like of them – from those that it is not permissible for him to see naked, whether male or female; then it is not allowed for him to enter upon them without seeking permission. This is the opinion of the Hanafis and the Maalikis. And seeking permission – according to them – in this case is obligatory; and it is not allowed to leave it off. To the extent the Maalikis say: whoever denies the obligation of seeking permission to enter has disbelieved, because it is from those things which are known from the religion by necessity.”
It further mentions:
“And the Shaafi`ees allow that a man enters upon those whom it is forbidden for him to marry – if they live with him – without seeking permission to enter. However it is upon him to notify them of his entrance with the like of him clearing his throat, or stamping of the shoes, and the like; so that those who are naked could cover up.”
Shaykh ibn Baaz rahimahullaah was asked :
Q: Regarding the people of a [single] household seeking permission when entering upon each other?
A: The Sunnah is that they seek permission when entering upon each other. This is what is legislated. Even the husband should seek permission when entering upon his wife; for he may see her in a condition that is not appropriate. So it is befitting that he seeks permission from his family, so that they know of his arrival. And if there was anything that they needed to cover up, they could cover it up – so that he is not offended by anything. The intent is that seeking permission to enter is required from the husband, the slave, the brother, the paternal uncle, and the like of them.
 Agreed upon. Reported by al-Bukhaaree no. 6241; & Muslim no. 2156.
 Chapter 486: When your Children reach Puberty. Shaykh al-Albaanee rahimahullaah said in his checking of ‘al-Adab al-Mufrad’ its chain of narration is authentic.
 Reported by al-Bukhaaree in ‘al-Adab al-Mufrad’, Chapter 487: Seeking Permission when entering where ones Mother is. Shaykh al-Albaanee rahimahullaah said its chain of narration is authentic. Also reported by at-Tabaraanee in ‘Musnad ash-Shaameeyeen’ pp. 360 from a chain of narration of Huzayl bin Shurahbeel that he said: “I heard Ibn Mas`ood saying: ‘Upon you is to seek permission from your mothers [i.e. when entering where they are].’ Shaykh al-Albaanee rahimahullaah said: “And its chain of narration is good. All of the narrators are reliable.”
 Reported by al-Bukhaaree in ‘al-Adab al-Mufrad’, Chapter 487: Seeking Permission when entering where ones Mother is. Shaykh al-Albaanee rahimahullaah said its chain of narration is good. And in a variant wording it occurs the saying: ‘You may see that which offends you.’
 Reported by al-Bukhaaree in ‘al-Adab al-Mufrad’, Chapter 488: Seeking Permission when entering where ones Father is. Shaykh al-Albaanee rahimahullaah graded it as having a weak chain of narration.
 Reported by al-Bukhaaree in ‘al-Adab al-Mufrad’, Chapter 490: Seeking Permission when entering where ones Sister is. Shaykh al-Albaanee rahimahullaah said its chain of narration is authentic. Ibn `Abbaas said: ‘So seeking permission is obligatory (upon all of the people).’
 Agreed upon. Reported by al-Bukhaaree no. 6241; & Muslim no. 2156.
 Sooratul-Hujuraat; (49):13
 Reported by al-Bukhaaree in ‘al-Adab al-Mufrad’, Chapter 491: Seeking Permission when entering where ones Brother is. Shaykh al-Albaanee rahimahullaah graded it as weak in his checking of ‘al-Adab al-Mufrad’.
 Reported by al-Bukhaaree in ‘al-Adab al-Mufrad’, Chapter 489: Seeking Permission when entering where ones Father or Son is. Shaykh al-Albaanee rahimahullaah graded it as weak in his checking of ‘al-Adab al-Mufrad’.
 Volume 3, pp. 146.
 See: Badaai` as-Sanaai` 5/124; & Ahkaamul-Qur∙aan of al-Jassaas 3/386; & ash-Sharh as-Sagheer 4/762; & Sharhul-Kaafee 2/1133; & al-Fawaakih ad-Dawaanee 2/427; & Tafseerul-Qurtubee 12/219.
 See footnote number 11.
 See: Mughnee al-Muhtaaj 4/199
 See: The Shaykh’s official website: http://www.binbaz.org.sa/node/8941