cover it. Al-Ḥāfiẓ Ibn Kathīr says in his Tafsīr:
“Meaning: they are not to show any part of their adornment to unrelated men except that which cannot possibly be concealed. Ibn Masʿūd said: such as the cloak and the garment—that is, the shawl Arab women customarily throw over their clothes—and whatever of the hem of their garments may appear; there is no blame on her for that, because it cannot be hidden.”
Al-Bukhārī 7/290 and Muslim 5/197 record from Anas (may Allah be pleased with him):
“On the Day of Uḥud the people fled from the Prophet ﷺ, while Abū Ṭalḥah stood in front of the Prophet ﷺ shielding him with his round shield¹. I indeed saw ʿĀʾishah bint Abī Bakr and Umm Sulaym with their skirts tucked up so that I could see the anklets on their calves; they were darting about² with water-skins on their backs, emptying them into the mouths of the soldiers.”
Al-Ḥāfiẓ Ibn Ḥajar al-ʿAsqalānī said: “This occurred before the obligation of ḥijāb, and it may also be that the exposure was unintended.”
I say: The interpretation we have given for the phrase “except what ordinarily appears thereof” (al-Nūr 31) is what the context most readily suggests. The early predecessors differed over its meaning; some maintained that it refers to the visible garments.
¹ A buckler-type shield.
² Moving quickly, skipping back and forth.