Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said concerning the saying of Allah Almighty: "Let those whom your right hands possess and those of you who have not reached puberty ask your permission three times" [Surah al-Nur: 58]: When a man is alone with his wife after the Isha prayer, no servant and no child should enter without permission until the morning prayer has been offered; and when he is alone with his wife at midday, it is the same. Then permission was given for them to enter without permission in the time between these, under the saying of Allah: "There is no blame on you or on them after these (times)" [Surah al-Nur: 58]. As for one who has reached puberty, he should not enter upon a man and his wife without permission under any circumstances, because Allah says: "And when the children among you reach puberty, let them ask permission" [Surah al-Nur: 59].
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13553
Ata' (may Allah have mercy on him) said: I said to Ibn Abbas (may Allah be pleased with them both): Two sisters of mine are under my care, and I spend on them. Should I also seek their permission (that is, when entering the house)? He answered yes. I said to him: That is a hardship for me. He said: Allah Almighty says: "O you who believe, let them ask your permission" [Surah al-Nur: 58]. Ibn Abbas (may Allah be pleased with them both) said: The command is to seek permission at these three times. Then he recited this verse: "And when the children reach (puberty)" [Surah al-Nur: 59].
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13554
Sayyiduna Ibn Abbas (may Allah be pleased with them both) used to say: There is a verse in which most people do not believe (i.e. they do not act upon it): the verse of permission. And I order even this slave-girl of mine (a short slave-girl of his who was standing by his head) to ask permission before coming in to me.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13555
Sayyiduna Hudhayfah (may Allah be pleased with him) was asked: Should a man ask permission before entering even upon his mother? He said: Yes; if he does not do so, he will see something that he dislikes.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13557
Ata bin Yasar (may Allah have mercy on him) said that a man asked the Prophet (peace and blessings be upon him): Should I ask permission even from my mother? He (peace and blessings be upon him) said: "Yes!" The man said: I live with her. He (peace and blessings be upon him) said: "Even so, ask permission." The man said: I serve her. He (peace and blessings be upon him) said: "Would you like to see her naked?" He said: No. He (peace and blessings be upon him) said: "Then ask permission."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13558
It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that two men asked (him) about (seeking) permission at the three times (mentioned) in the Qur'an. Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said: "Allah Almighty is the Concealer of faults and loves concealment." People had no curtains on their doors, nor curtained enclosures in their houses, so sometimes a man's servant, or his child, or an orphan who was under his care would suddenly come in upon him while he was with his wife. So Allah Almighty commanded that they should seek permission at those times which Allah Almighty has mentioned. Then Allah Almighty granted them curtains and their provision was expanded, so they made curtains as well, and people thought that this sufficed in place of the permission which Allah Almighty had commanded.
The Shaykh (may Allah have mercy on him) said: The hadith of Ubaydullah bin Abi Yazid and of Ata weakens this narration; and Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13559