Short answer
Showing hair on purpose in front of non-mahram men is a sin, even a little at the front. If it slips out by accident, cover it and there is no sin. In salah the Hanafi rule is precise: if a quarter of the hair shows for the time of one pillar of the prayer, the prayer is invalid; less than that makes it disliked.
The hair is awrah, so deliberately leaving any of it uncovered before non-mahram men is sinful. In prayer, uncovering a quarter of the hair for the length of one rukn (about the time it takes to say SubhanAllah three times) invalidates the prayer, and uncovering it by her own act invalidates it at once. Less than a quarter does not invalidate it, but it is makruh.
Other madhhabs
- Shafi'i
- Any part of the awrah uncovered in prayer, even a little hair, invalidates it unless it is covered straight away.
- Hanbali
- A small amount uncovered is excused even if it lasts; a large amount invalidates the prayer unless it is covered at once.
Explanation
Many sisters wear the hijab with a fringe or the front of the hair showing. It is a common style, but the hair is part of the awrah, and the Quran asks women to cover their adornment and draw the head cover down. A few locks on show is a smaller gap than no hijab, but it is still a gap to close.
Outside prayer:
- On purpose: sinful, even if only the front shows. An underscarf or bonnet keeps everything in place.
- By accident: wind, a slipped scarf or a fall is not a sin. Cover it as soon as you notice.
- At home with mahrams: no issue. See who is a mahram.
In salah covering is a condition of the prayer itself, even alone in a closed room. The Prophet ﷺ said Allah does not accept the prayer of a woman past puberty without a head cover. The Hanafi school measures exposure by quarters. If a quarter of your hair shows for the length of one pillar of the prayer, the prayer is invalid and must be repeated. If you uncover it deliberately during the prayer, it is invalid straight away. If less than a quarter shows, the prayer is valid but disliked.
So if your scarf slips in sujud and you fix it at once, your prayer stands. If much of your hair hangs out under a short scarf for the whole prayer, repeat it. A simple prayer garment that covers you from head to toe solves this. See do you need hijab to pray at home and how women pray.
The evidence
Quran, Surah An-Noor 24:31
وَقُل لِّلْمُؤْمِنَٰتِ يَغْضُضْنَ مِنْ أَبْصَٰرِهِنَّ وَيَحْفَظْنَ فُرُوجَهُنَّ وَلَا يُبْدِينَ زِينَتَهُنَّ إِلَّا مَا ظَهَرَ مِنْهَا ۖ وَلْيَضْرِبْنَ بِخُمُرِهِنَّ عَلَىٰ جُيُوبِهِنَّ ۖ وَلَا يُبْدِينَ زِينَتَهُنَّ إِلَّا لِبُعُولَتِهِنَّ أَوْ ءَابَآئِهِنَّ أَوْ ءَابَآءِ بُعُولَتِهِنَّ أَوْ أَبْنَآئِهِنَّ أَوْ أَبْنَآءِ بُعُولَتِهِنَّ أَوْ إِخْوَٰنِهِنَّ أَوْ بَنِىٓ إِخْوَٰنِهِنَّ أَوْ بَنِىٓ أَخَوَٰتِهِنَّ أَوْ نِسَآئِهِنَّ أَوْ مَا مَلَكَتْ أَيْمَٰنُهُنَّ أَوِ ٱلتَّٰبِعِينَ غَيْرِ أُو۟لِى ٱلْإِرْبَةِ مِنَ ٱلرِّجَالِ أَوِ ٱلطِّفْلِ ٱلَّذِينَ لَمْ يَظْهَرُوا۟ عَلَىٰ عَوْرَٰتِ ٱلنِّسَآءِ ۖ وَلَا يَضْرِبْنَ بِأَرْجُلِهِنَّ لِيُعْلَمَ مَا يُخْفِينَ مِن زِينَتِهِنَّ ۚ وَتُوبُوٓا۟ إِلَى ٱللَّهِ جَمِيعًا أَيُّهَ ٱلْمُؤْمِنُونَ لَعَلَّكُمْ تُفْلِحُونَ ﴿٣١﴾
And tell the believing women to reduce [some] of their vision and guard their private parts and not expose their adornment except that which [necessarily] appears thereof and to wrap [a portion of] their headcovers over their chests and not expose their adornment except to their husbands, their fathers, their husbands' fathers, their sons, their husbands' sons, their brothers, their brothers' sons, their sisters' sons, their women, that which their right hands possess, or those male attendants having no physical desire, or children who are not yet aware of the private aspects of women. And let them not stamp their feet to make known what they conceal of their adornment. And turn to Allah in repentance, all of you, O believers, that you might succeed.
Commands believing women to draw their head covers over their chests and not to show their adornment except to close family.
Sunan Abi Dawud 641
Graded sahih... لا يقبل الله صلاة حائض إلا بخمار ...
"Allah does not accept the prayer of a woman who has reached puberty except with a head cover."
Covering the hair is a condition of a woman's prayer.
Where the ruling is recorded
- al-Durr al-Mukhtar, Kitab al-Salah, chapter on the conditions of prayer, covering the awrah. Uncovering a quarter of a part of the awrah for the time of a rukn prevents the prayer; by her own act it invalidates it at once.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Salah, chapter on the conditions of prayer, covering the awrah. The hair hanging down from the head is counted as awrah on the sound view.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.