Do the angels refrain from attending a place where there is a bare-headed woman?
Question

It has become a widespread habit among women to wear hijab during halaqahs (study circles) because the angels attend and may feel embarrassed to see the women when they are not covering their heads.
Praise be to Allah.Firstly:
We do not know of anything in the clear, soundly-narrated religious texts to indicate that the angels do not attend gatherings in which women uncover their hair.
It is proven from the Prophet (blessings and peace of Allah be upon him) that the angels do not enter houses in which there is a dog, an image, a person who is junub or a bell [although there are differences of opinion regarding the soundness of the hadiths which mention a person who is junub and a bell].
There is no reference in these reports to the presence of bare-headed woman. If that was one of these things [that prevent the angels from attending], the Prophet (blessings and peace of Allah be upon him) would have pointed it out, as he pointed out other things.
In Saheeh al-Bukhaari (3775), it is narrated that the Prophet (blessings and peace of Allah be upon him) said: “O Umm Salamah, do not bother me concerning ‘Aa’ishah, for it – by Allah – the revelation never came down to me when I was under a blanket with any of you except her.
This indicates that Jibreel used to bring down the revelation to the Prophet (blessings and peace of Allah be upon him) when he was with ‘Aa’ishah under the same blanket, and it is well known that when a woman is under her blanket, she does not wear full hijab.
Secondly:
Some may quote as evidence for that the report which was narrated by at-Tabaraani in al-Mu‘jam al-Awsat (6/287), from Umm Salamah, from Khadeejah (may Allah be pleased with her), who said: I said: O Messenger of Allah, O son of my paternal uncle, when that one who comes to you comes to you, can you tell me?
The Messenger of Allah (blessings and peace of Allah be upon him) said to me: Yes, O Khadeejah.
Khadeejah said: Jibreel came to him one day when I was with him.
The Messenger of Allah (blessings and peace of Allah be upon him) said: O Khadeejah, this companion of mine who comes to me has come to me.
I said to him: Get up and sit on my right thigh.
So he got up and sat on my right thigh.
I said to him: Do you still see him?
He said: Yes.
I said to him: Move and sit on my left thigh.
He did that, then I said: Do you still see him?
He said: Yes.
I said to him:
Turn around and sit in my lap.
He did that, then I said to him: Do you still see him?
He said: Yes.
Khadeejah said: Then I uncovered my hair and threw my headcover aside, and said to him: Do you still see him?
He said: No.
I said to him: This is a noble angel. No, by Allah, this is not a devil… End quote.
But this hadith is da‘eef (weak) and cannot be relied upon as evidence concerning this issue. Shaykh al-Albaani explained the reasons why it is weak in Silsilat al-Ahaadeeth ad-Da‘eefah (6097).
Dr. Akram Diya’ al-‘Umari said: There are reports which are weak (da‘eef), or have flimsy isnaads or odd texts, which suggest that Khadeejah ascertained that the one whom the Messenger saw was an angel and not a devil." (As-Seerah an-Nabawiyyah as-Saheehah  1/128).
Thirdly:
Some people may quote as evidence for that the report narrated in Saheeh Muslim (974) about the Prophet (blessings and peace of Allah be upon him) going out to al-Baqee‘, and his saying to ‘Aa’ishah: “Jibreel came to me when you saw. He called me but he concealed it from you, and I answered him but I concealed it from you. He would not enter the house when you were not fully dressed…”
Ibn Hibbaan included this report in a chapter entitled: Explanation that Jibreel (peace be upon him) would not enter the house of the Prophet (blessings and peace of Allah be upon him) when ‘Aa’ishah was not fully dressed." (Saheeh Ibn Hibbaan  16/45).
But this hadith does not clearly state that the angels do not enter a place in which a woman has taken off her hijab (headcover), for the following reasons:
1.. The phrase “not fully dressed” refers to something more than uncovering the head, so the fact that he did not enter when she was not fully dressed does not mean that he would not enter if only her hair was uncovered.
Especially since not being fully dressed means taking off some clothes, which is appropriate for the one who wants to sleep, especially in hot countries. This is something other than merely uncovering the hair.
2.. It is possible that this is something that applied only to the wives of the Prophet (blessings and peace of Allah be upon him, or only to Jibreel, as may be understood from the comments of Ibn Hibbaan.
And Allah knows best.