What is the Khimar?
Those who argue that niqab is fard often attempt to argue that the khimar commanded by Surah an-Nur ayah 31 is a niqab, i.e., it covers the face. This is simply not the case. Here is proof.
What does the word khimar mean in classical Arabic?
In common usage, the face and the head are distinguished. For instance, in wudu, we wash the "face" and the "head" separately. In order to say that something covers the face it is necessary to state explicitly that it covers the face; saying that it covers the "head" is not enough. Here are some explanations of the linguistic meaning of "khimar":
Imam Abu'l-Fida ibn Kathir: "Khumur is the plural of khimar which means something that covers, and is what is used to cover the head. This is what is known among the people as a khimar."
The dictionary of classical Arabic, Aqrab al-Mawarid: "[The word khimar refers to] all such pieces of cloth which are used to cover the head. It is a piece of cloth which is used by a woman to cover her head."
Shaykh Muhammad al-Munajjid on Islam Q&A: "Khimaar comes from the word khamr, the root meaning of which is to cover. For example, the Prophet (peace and blessings of Allaah be upon him) said: “Khammiru aaniyatakum (cover your vessels).” Everything that covers something else is called its khimaar. But in common usage khimaar has come to be used as a name for the garment with which a woman covers her head; in some cases this does not go against the linguistic meaning of khimaar. Some of the fuqahaa’ have defined it as that which covers the head, the temples and the neck. The difference between the hijaab and the khimaar is that the hijaab is something which covers all of a woman’s body, whilst the khimaar in general is something with which a woman covers her head."
Shaykh Muhammad Nasiruddin Albani: "The word khimaar linguistically means only a head covering. Whenever it is mentioned in general terms, this is what is intended."
Each of these authorities has stated that the khimar covers the head not the "face".
How is the khimar to be worn?
In case the above is not convincing that the khimar covers the head but not the face, here are specific descriptions given in the tafasir of how exactly Allah SWT has commanded the khimar to be worn:
Imam Abu Abdullah Qurtubi: "Women in those days used to cover their heads with the khimar, throwing its ends upon their backs. This left the neck and the upper part of the chest bare, along with the ears, in the manner of the Christians. Then Allah commanded them to cover those parts with the khimar."
Imam Abu'l-Fida ibn Kathir: "'Draw their khumur to cover their bosoms' means that they should wear the khimar in such a way that they cover their chests so that they will be different from the women of the jahiliyyah who did not do that but would pass in front of men with their chests uncovered and with their necks, forelocks, hair and earrings uncovered."
From the above we can see that the khimar covered the hair, but left the forehead, ears, neck, and upper chest uncovered. When Allah SWT commanded the women to draw their khimars to cover their bosoms, the women were to draw the ends of the khimar forward and fasten it so that their foreheads, ears, necks, and upper chests were covered. This does not mention the covering of the face. If Allah SWT had meant the women to cover their faces with their khimars, Imam Qurtubi and Imam ibn Kathir would have described this. They did not. The khimar is a headscarf, period.
Wearing the khimar in salat
A hadith sets out a rule for the woman offering salat:
Abu Dawud Book 2 #641. Narrated Aisha, Umm al-Mu'minin "The Messenger of Allah said, 'Allah does not accept the prayer of a woman who has reached puberty unless she wears a khimar'."
This means that whenever a woman has to offer salat, even if she is completely alone, she must wear a khimar. The scholars are UNANIMOUS that a woman may uncover her face in private salat. If a woman must wear a khimar, yet she is permitted to display her face then clearly the khimar is not a niqab. If it were, she would be offering salat in private with her face veiled, but she does not do so. The conclusion is plain: the khimar is NOT a niqab. The khimar is a headscarf.
In the dalils that are presented for niqab is a hadith that is translated as "tore their garments and covered their faces with the cut pieces".
In fact, the Arabic text of this hadith says that they tore their garments and ikhtamarna bi ha. This means that they made khimars from the garments. The word "faces" DOES NOT APPEAR in the Arabic text. It DOES NOT. Ibn Hajar, who wrote a commentary on Sahih Bukhari says that "ikhtamarna" should be translated as "covered themselves" and that it means "covered their faces". But this is his opinion. There is no word "faces" in the Arabic text of this hadith.
It has been proved above that the khimar is a HEADSCARF. That is what the women made from their torn-up garments.
The hadith is cited to "prove" that the women obeyed Surah an-Nur ayah 31 by wearing niqab. But it does not prove this. Imam Qurtubi and Imam ibn Kathir have provided an explicit description of what the khimar is to cover. This is the forehead, hair, ears, neck, and upper chest. THEY DO NOT MENTION THE FACE. And neither does the hadith.
There is no evidence that the women began wearing niqab to obey Surah an-Nur ayah 31. None. Not in the hadith that is cited, and not in the tafasir. If there is some proof that niqab is fard, it is not in the khimar.