Shaykh Salih al-Fawzan (may Allah preserve him) said:
The correct view as indicated by the evidence is that the woman’s face is ‘awrah which must be covered. It is the most tempting part of her body, because what people look at most is the face, so the face is the greatest ‘awrah of a woman. This is in addition to the shar’i evidence which states that it is obligatory to cover the face.
For example, Allah says (interpretation of the meaning): “And tell the believing women to lower their gaze (from looking at forbidden things), and protect their private parts (from illegal sexual acts) and not to show off their adornment except only that which is apparent (like both eyes for necessity to see the way, or outer palms of hands or one eye or dress like veil, gloves, headcover, apron), and to draw their veils all over Juyoobihinna (i.e. their bodies, faces, necks and bosoms)…” [al-Noor 24:31]
Drawing the veil all over the juyoob implies covering the face.
When Ibn ‘Abbas (may Allah be pleased with him) was asked about the ayah (interpretation of the meaning): “O Prophet! Tell your wives and your daughters and the women of the believers to draw their cloaks (veils) all over their bodies” [al-Ahzab 33:59] –
he covered his face, leaving only one eye showing. This indicates that what was meant by the ayah was covering the face. This was the interpretation of Ibn ‘Abbas (may Allah be pleased with him) of this ayah, as narrated from him by ‘Ubaydah al-Salmaani when he asked him about it.
In the Sunnah there are many ahadith, such as: the Prophet (peace and blessings of Allah be upon him) said: “The woman in ihram is forbidden to veil her face (wear niqab) or to wear the burqa’.” This indicates that when women were not in ihram, women used to cover their faces.
Fatawa al-Mar’ah al-Muslimah, 1/396, 397