Abu Dawud

640. Commentary:
➊ Both of these narrations are weak. Therefore, it is not obligatory for a woman to cover her feet during prayer; at most, it can be considered preferable in light of the general command of modesty. Some scholars use another narration as evidence for covering the tops of the feet, in which it is mentioned that the Prophet sallallahu alayhi wa sallam, in response to a question from Umm Salamah radi Allahu anha, said that if a woman's feet become exposed when her garment hangs down more than a handspan from men's clothing, then women should let their garments hang down by a forearm's length. [ترمذي، حديث : 1831]
From this, they try to establish that a woman should cover her entire body, including the tops of her feet, during prayer. However, this hadith of Umm Salamah radi Allahu anha pertains to the general command of modesty, and making it obligatory for a woman praying is incorrect. If this were the case, then it would also be necessary for a woman to cover her face while praying, because the face is also included in the command of modesty. If it is not obligatory for a woman to cover her face during prayer, then it is also incorrect to make it obligatory to cover the tops of her feet during prayer based on the hadith of Umm Salamah radi Allahu anha. For further details, see: [فتاوي شيخ الاسلا م ابن تيميه : 11؍ 426- 430 طبع جديد، 1998ء الرياض]
➋ These ahadith being marfu‘ (i.e., attributed to the Prophet sallallahu alayhi wa sallam) is not established, but it is better for a woman to cover her entire body during prayer (because she is commanded to cover her whole body including the head). It is worth considering that if such strictness regarding modesty is required of a woman in the pure environment of the mosque and during the act of worship like prayer, then how much more should she observe her modesty when going out in open places and among strangers!