Covering the ‘Awrah is the first thing that a woman must do when praying, because covering the ‘Awrah is one of the conditions of prayer that must be given due attanetion. Hence the prayer that must be given due attention. Hence the prayer of one who is naked or who does not cover her whole ‘Awrah is not valid.
The evidence that it is obligatory to cover the Awrah in prayer is the Verse in which Allaah says:
‘O Children of Adam! Take your adornment (by wearing your clean clothes) while praying.’ (Qur’aan 7:31)
Ibn Hazm narrated that there was scholarly consensus on the fact that what is meant by this is covering the ‘Awrah. [See Fath Al-Baari, 1/554]
All of the woman is ‘Awrah except her face and hands. She must cover every part of her body except the face and hands.
Women should note that the tops of the feet come under the general meaning of the woman’s ‘Awrah, so they must be covered. That is because of the Hadeeth of the Mother of the Belivers Umm Salamah who said: ‘What should women do with their hems, O Messenger of Allaah?’ He said: ‘Let them lower them by a handspan.’ She said: ‘But then their feet will show.’ He said: ‘Let them lower them by a cubit, but no more than that.’ [At-Tirmidhi]
Based on the above, a woman should wear something when praying that will cover her ‘Awrah as defined above. The scholars differed as to what a woman should wear when praying.
It was narrated that ‘Umar ibn Al-Khattaab said: A woman should pray in three garments. [Ibn Abi Shaybah]
It was narrated that ‘Abdullah ibn ‘Umar said: When a woman prays, let her pray in all her garments: her chemise her head cover and her Milhafah (wrapper). [Ibn Abi Shaybah]
All of this is to emphasise the importance of covering. If a woman prays in a single loose-fitting garment that covers her ‘Awrah, that is permissible, because she has been commanded to cover her ‘Awrah, but no specific details have been stipulated.
Ibn Al-Mundhir Al-Nisaboori said:
‘A woman should cover all of her body when praying, except her face and hands, and it is sufficient for her to pray in one garment, or two, or more than that, if it covers what she is obliged to cover whilst praying. I do not think that the reports from the earliest Muslims about covering with three or four garments were intended as anything more than a recommendation to be on the safe side, but Allaah knows best. I do not know of anyone among the scholars who enjoined repeating the prayer if a woman prays in a single garment, so long as that garment covers what she is required to cover.’
I say: This view is confirmed by the Sunnah, namely the report of the Mother of the Believers, ‘Aishah radiaAllahu anha who said: The believing women used to attend Fajr prayer with the Messenger of Allah (sallahu alahi wassalam), wrapped up in their aprons. [Al-Bukhaari]
The point here is that they used to pray with the Prophet sallahu alahi wassalam in this manner, and the report indicates that they made do with wrapping themselves in their aprons, and the apron is a single garment.
If a little of a woman’s ‘Awrah becomes uncovered unintentionally whilst she is raying, such as part of her hair or part of her shin, or a little of her forearm, she will not be brought to account for that inshaAllaah, and her prayer remains valid, so long as that happened without her realizing it.
The evidence for that is the Hadeeth of Salamah Al-Jurami who said that he used to lead his people in prayer when he was six or seven years old. He said: I used to wear a Burdah (cloak) which, when I prostrated, would roll up (and uncover me). A woman among the tribe said: ‘Why don’t you cover the backside of your reader for us?’ So they bought (some fabric) and made me a shirt from it, and I never rejoiced over anything as much as I did over that shirt. [Al-Bukhaari]
Shaykh Al-Islam Ibn Taymiyah [Majmoo’ Al-Fataawa, 22/123] (may Allaah have mercy on him) said:
‘If a little of her hair or body becomes uncovered, she does not have to repeat her prayer according to the majority of scholars. This is the view of Abu Haneefa and Ahmad. But if a lot becomes uncovered, then she should repeat the prayer whilst the time for it is still in effect, according to most of the scholars, including the four Imaams and others.’