A Comprehensive Answer by Shaykh Ibn Baz Regarding Hijab and Uncovering

Answer:
In the name of Allah, the Most Gracious, the Most Merciful. Praise be to Allah, and may Allah send blessings and peace upon the Messenger of Allah, and upon his family and his Companions.
As for what follows:
In continuation of the question asked about hijab and uncovering:
It has been established that it is obligatory to observe hijab and to stay away from the causes of fitnah (trial, discord or temptation) for women who are not of the advanced age, and the evidence for this matter has been presented. Whoever permits a woman who is not of the advanced age to uncover has erred, whether his intention is good or bad. And whoever exercises independent legal reasoning in this matter has the reward of ijtihad, even if he misses the reward of being correct.
Those who permit uncovering have relied on hadiths in which some uncovering of women is mentioned, and they assumed that this was after the hijab was prescribed. This is not the case; rather, the hadiths that mention uncovering were from before the hijab. Once the hijab was revealed, the believing women were bound by it and they observed hijab.
Among the things they relied on is also the hadith of the woman from Khath'am, who said to the Messenger of Allah (peace and blessings be upon him) on the Day of Sacrifice, on the night of Muzdalifah, the night of the Day of Sacrifice: "The obligation of Allah upon His servants has overtaken my father, an old man who cannot stay on the mount. May I perform Hajj on his behalf?" He said: . She was addressing the Prophet (peace and blessings be upon him) while he was on the mount, and al-Fadl ibn al-Abbas was riding behind him. Al-Fadl kept looking at her and she kept looking at him, and the Prophet (peace and blessings be upon him) kept turning al-Fadl's face to the other side. They said: This is evidence that she was uncovered, and this was after the hijab, and in the last days of the Prophet's (peace and blessings be upon him) life.
The answer to this is: It is prohibited. There is no evidence that she was uncovered. The mere fact that he looked at her and she looked at him does not imply uncovering, nor does it necessitate uncovering. She may have looked at him from behind the hijab, and he may have looked at her from behind the hijab. This is a real possibility. He may have looked at her stature and build, and heard her voice, and so on. It does not follow from this that she was uncovered.
Then, even if it were assumed that she was uncovered, this would be an argument for those who say: Uncovering is permissible specifically in Hajj; because of his saying (peace and blessings be upon him): . He forbade her from wearing the niqab (face veil) while in the state of ihram (the consecrated state of pilgrimage) in Hajj and 'Umrah (the lesser pilgrimage). So if it were assumed that this woman was uncovered, this would pertain to the state of ihram. Even though the correct view in the state of ihram is that she should not uncover either, and that she must observe hijab even in the state of ihram. And his saying (peace and blessings be upon him): means: Do not wear the niqab, which is a thing made for the face, with which the face is covered, and it has an opening for one eye or for both eyes. The woman was forbidden from wearing this, just as she was forbidden from wearing gloves, which are coverings for the hands. She was forbidden from this during the state of ihram in Hajj and 'Umrah: Do not wear gloves, and do not wear the niqab which is made for the face.
As for her letting her khimar (head covering) or jilbab (outer garment) hang down over her face, she is not forbidden from this, and by this the covering is achieved. For this reason, in the hadith of 'A'ishah regarding the Farewell Pilgrimage, she said: "We were with the Prophet (peace and blessings be upon him), and when the men came near us, one of us would let her jilbab hang down from above her head over her face, and when they moved away, we would uncover it." She clarified that they used to observe hijab and hide their faces even in the Farewell Pilgrimage. This indicates that the face is covered and veiled after the hijab, even in Hajj and 'Umrah.
Thus, it is known by this that the hadith of the woman from Khath'am is not an argument for the proponents of uncovering and those who advocate for uncovering.
They also rely on a hadith narrated by Abu Dawud from 'A'ishah (may Allah be pleased with her), who said: "Asma' bint Abi Bakr came to visit me," meaning: her sister (may Allah be pleased with them all), the wife of al-Zubayr. She said: "And she was wearing thin clothes, so the Prophet (peace and blessings be upon him) turned his face away from her and said: and pointed to his face and his two hands." They said: This is evidence that the woman uncovers her face and her two hands for unrelated men; because of his saying (peace and blessings be upon him) to Asma': and pointed to his face and his two hands.
The answer is: This is weak in its chain of narration, its text is denounced, and it is not an argument. As for the denunciation of the text, it is because it is not fitting for Asma', who is among the special Muhajirat (female emigrants) and among the special believing women, to be in this state, and to wear thin clothes in the presence of the Messenger of Allah (peace and blessings be upon him), the husband of her sister! It is not fitting for her given her faith and her mindfulness of Allah.
As for the chain of narration, it is weak according to the scholars due to three defects in the chain, three defects that indicate its weakness and lack of authenticity:
The first is that it is from the narration of Sa'id ibn Bashir, who is weak and his narration is not relied upon.
The second is that it is from the narration of Khalid ibn Duraik from 'A'ishah, and he did not hear from her, so it is a report with a broken chain.
The third is that it is from the narration of Qatadah from Khalid using the expression "from" (an-en'anah), and Qatadah is one who conceals defects in chains (tadlis). When he uses this expression, his narration is not accepted, and it is not relied upon except in "the two Sahihs" (al-Bukhari and Muslim).
So these are three defects in this hadith, along with the denunciation of its text.
Even if it were assumed to be authentic, this would have been before the hijab. For before the hijab, there is no harm in a woman uncovering her face and her two hands in the presence of men. Then that was abrogated, and it was forbidden after the hijab; because there is no explicit statement in the hadith that this was after the hijab. It is possible that it was before the hijab if it were authentic.
So it is known by this that there is no proof in it, due to its weakness and the anomaly of its text, and because it is not explicit that it is after the hijab. Thus, no proof remains in the hands of these claimants for the exposure of the woman, and that there is no harm in it; no proof remains in their hands to counter the evidence from the Book and the Sunnah indicating the obligation of the hijab for the woman after the revelation of the verse of the hijab, and that it is the truth. Then, what is known by the people of knowledge and insight is what is in the exposure of the face in terms of fitnah (trial, discord or temptation) and causes of danger. This meaning for which the verse of the hijab was revealed exists in the exposure and display of the face. Indeed, the exposure of the faces of beautiful women is a great fitnah (trial, discord or temptation), and from the wisdom of Allah (Glorified and Exalted is He) is that He forbade that, blocked the door, and cut off the root of this evil, for what the Noble Book and the Pure Sunnah brought.
As for the women of advanced age - and they are the old women - their matter is different. Allah the Exalted said: [al-Nur:60]. If they are in this state: an old woman who does not hope for marriage and does not display adornment, then there is no blame on her if she uncovers; because she is not a place for fitnah; being an old woman who does not display adornment, and does not hope for marriage. Then He said after that: [al-Nur:60]. So He (Glorified and Exalted is He) clarified that their observing hijab and their modesty is better for them, even if they are old women. [al-Nur:60]. If the modesty of old women is better for them, how much more so is the case for young women and those in the category of young women?
So the danger is clear, and the wisdom in the prohibition is clear. And Allah (Exalted and Majestic is He) is the One who grants success.