Question asked to Al Imaam Al-Albaani (may Allaah have mercy upon him):
Q. Is the Muslim woman to pray in the clothes she wears in her house which cover her, or is it a must that there be a Jilbaab over her? Also, is it a must that she cover her feet in the prayer?
A. As for covering the feet in the prayer, then this is a must. That is because the feet are from the Awrah (the areas that must be covered) just as the Qur'aan and the Sunnah have indicated. As for, if it is permissible for her to pray in her house clothes? That which is apparent is that her house clothes do not cover her feet. Therefore, the answer is clear. It is not permissible for her to pray in her house clothes. Based on this, there has come in some of the Salafee narrations that the woman, when she stands to pray, it is obligatory upon her to have upon herself a long garment to cover the top part of her feet. Except, if we were to say that there's a woman -and this is an imagination- that lives in her own home covered in Jilbaab as if she was living amongst foreign men. It is possible that there is a woman who has something of tightness in her house clothing. If she prays, and at the same time she's covering her awrah, however from another angle her clothing describes her awrah (because of it being tight), this is an opposition to the legislation of her Lord. So based upon this, it is a must that the woman take an Izaar or a long Qamees to wear (to cover herself in prayer) even if her feet are uncovered. It is sufficient for her to cover the top of her feet with this long garment."
Source: Al Fataawaa Al-Usturaaliyyah pg. 125
Sisters Upon Al-Istiqaamah