Niqaab is part of Islam
17-5-2016 | IslamWeb
Question:
Assalaamu alaykum. What is the ruling on the one who says that the niqab is not part of Islam and that it is a Persian custom that seeks to enslave women and rob them of their rights? Has the niqab been proven to be a part of Islam through textual evidence? And is the one who denies it considered a nonbeliever?
Answer:
All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad 
is His slave and Messenger.
Covering the face with the niqaab or with something else is permissible according to the agreement of the scholars of Fiqh. There are many pieces of evidence that show the order for wearing it as well as its legitimacy.
It is enough to mention two pieces of evidence here:
1- Allaah says (what means): {O Prophet, tell your wives and your daughters and the women of the believers to bring down over themselves [part] of their outer garments. That is more suitable that they will be known and not be abused. And ever is Allaah Forgiving and Merciful.} [Quran 33:59] The prominent interpreter of the Quran, At-Tabari 
reported from Ibn Abbaas 
that he interpreted this verse saying, “Allaah commanded the believing women that if they go out of their homes for a necessity to cover their faces from above their heads with their garments and show only one eye.” At-Tabari also reported such meaning from ‘Abeedah As-Salmaani .
2- Allaah says (what means): {…and to wrap [a portion of] their head covers over their chests.} [Quran 24:31] Al-Bukhaari wrote a chapter, which he entitled: {and to wrap [a portion of] their head covers over their chests}. Under this chapter, he quoted the hadeeth by ‘Aa’ishah 
who said, “May Allaah have mercy on the first migrant women because when Allaah sent down {and to wrap [a portion of] their Khimaars over their chests} they tore their garments and used them as Khimaars." Ibn Hajar said in Al-Fat-h, “They used them as Khimaars means that they covered their faces with them.” Ash-Shinqeeti said in Adhwaa’ Al-Bayaan, “A fair person undoubtedly realizes that a woman wearing hijab in front of men and her covering her face in front of them has been confirmed by the authentic Sunnah, which explains the Book of Allaah Almighty.” There are many pieces of evidence about the legitimacy of covering the face, but this is not the place to mention them all. Please, refer to fataawa 300796 and ’s wives">115107.
The difference of opinion among the scholars is only regarding whether it is obligatory or recommended. We already highlighted this matter in fatwa 92091.
As regards the saying that it is a habit – which is the view of some contemporaries – then this is an opinion to which no one has preceded them as far as we know.
Imaam Ahmad indeed spoke well when he said to one of his students, “Beware of saying a statement which no predecessor has preceded you in.”
Shaykh Abu Bakr Al-Jazaa'iri, may Allaah protect him, said in Aysar At-Tafaaseer, “Covering the face from non-Mahram (marriageable) men is the Sunnah of the believing women from a very old age, and not as the people of falsehood say that it is a habit of the Pre-Islamic Era of Ignorance. The two daughters of Shu’ayb grew up in the house of Prophecy, purity and chastity, and one of them covered her face from Moosa (Moses) out of bashfulness and piety.”
However, if a scholar says that it is not legitimate to cover the face, then he is not ruled to be a disbeliever because they have a misconception and misinterpretation about it. Shaykh Abdullaah Al-Jibreen said:
“In general, misinterpretation is one of the most important impediments that prevents declaring a specific person as a non-believer. It is for this reason that some scholars said that if evidence reached a person who misinterprets the text and does not retract his view, and it is in regard to an issue wherein it is probable for someone to make a mistake, and it is probable for the person who made a mistake that the misconception stays in his heart because of misconceptions that were raised around it or due to accompanying circumstances in a particular incident, then he is not ruled to be a non-believer, as Allaah says (what means): {And there is no blame upon you for that in which you have erred but [only for] what your hearts intended.} [Quran 33:5]
It is for this reason that some scholars did not rule some specific people of the Jahmiyyah sect, who believed in some beliefs that take a person out of the fold of Islam in regard to some Names and Attributes of Allaah, to be non-Muslims…”
Allaah knows best.