The Messenger of Allah ﷺ said: If anyone who is sexual defiled leaves a spot equal to the breadth of a hair without washing, such and such an amount of Hell-fire will have to be suffered for it. Ali said: On that account I treated my head (hair) as an enemy, meaning I cut my hair. He used to cut the hair (of his head). May Allah be pleased with him.

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ مَنْ تَرَكَ مَوْضِعَ شَعْرَةٍ مِنْ جَنَابَةٍ لَمْ يَغْسِلْهَا فُعِلَ بِهِ كَذَا وَكَذَا مِنَ النَّارِ قَالَ عَلِيٌّ فَمِنْ ثَمَّ عَادَيْتُ رَأْسِي فَمِنْ ثَمَّ عَادَيْتُ رَأْسِي ثَلاَثًا وَكَانَ يَجِزُّ شَعْرَهُ

The Prophet said: "Whoever leaves an area the size of a hair on his body and does not cleanse it from sexual impurity, such and such will be done to him in the Fire." 'Ali said: "Because of that I am hostile towards my hair," and he used to shave his head.

عَنِ النَّبِيِّ ﷺ قَالَ مَنْ تَرَكَ مَوْضِعَ شَعَرَةٍ مِنْ جَسَدِهِ مِنْ جَنَابَةٍ لَمْ يَغْسِلْهَا فُعِلَ بِهِ كَذَا وَكَذَا مِنَ النَّارِ قَالَ عَلِيٌّ فَمِنْ ثَمَّ عَادَيْتُ شَعَرِي وَكَانَ يَجُزُّهُ

I heard the Prophet ﷺ say: ʿWhoever leaves a space the size of a hair when doing ghusl for janabah and does not make water reach it, Allah will punish him with such and such in the Fire.” ‘Ali ؓ said: From that time I disliked my hair.

سَمِعْتُ النَّبِيَّ ﷺ يَقُولُ مَنْ تَرَكَ مَوْضِعَ شَعَرَةٍ مِنْ جَنَابَةٍ لَمْ يُصِبْهَا مَاءٌ فَعَلَ اللهُ تَعَالَى بِهِ كَذَا وَكَذَا مِنَ النَّارِ قَالَ عَلِيٌّ فَمِنْ ثَمَّ عَادَيْتُ شَعْرِي

I heard the Prophet ﷺ say: “Whoever leaves a space the size of a hair on his side when doing ghusl for janabah and does not make water reach it, Allah will punish him with such and such of fire.ʿ ʿAli ؓ said: From that time I disliked my head (i.e., hair).

سَمِعْتُ النَّبِيَّ ﷺ يَقُولُ مَنْ تَرَكَ مَوْضِعَ شَعَرَةٍ مِنْ جَسَدِهِ مِنْ جَنَابَةٍ لَمْ يُصِبْهَا الْمَاءُ فُعِلَ بِهِ كَذَا وَكَذَا مِنَ النَّارِ قَالَ عَلِيٌّ فَمِنْ ثَمَّ عَادَيْتُ رَأْسِي فَمِنْ ثَمَّ عَادَيْتُ رَأْسِي

I heard the Messenger of Allah ﷺ say: Whoever leaves a space the size of a hair [when doing ghusl for janabah] and does not pour water on it, such and such will be done to him in the Fire. ‘Ali ؓ said: From that time I hated my hair, as you can see.

سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ مَنْ تَرَكَ مَوْضِعَ شَعَرَةٍ مِنْ جَنَابَةٍ لَمْ يُصِبْهَا الْمَاءُ فُعِلَ بِهِ كَذَا وَكَذَا مِنَ النَّارِ قَالَ عَلِيٌّ فَمِنْ ثَمَّ عَادَيْتُ شَعْرِي كَمَا تَرَوْنَ

I heard the Prophet ﷺ say: ʿWhoever leaves a space the size of a hair when doing ghusl for janabah and does not make water reach it, Allah will punish him with such and such in the Fire.” ‘Ali ؓ said: From that time I disliked my hair. (Using translation from Aḥmad 727)

سَمِعْتُ النَّبِيَّ ﷺ قَالَ مَنْ تَرَكَ مَوْضِعَ شَعْرَةٍ مِنْ جَسَدِهِ مِنْ جَنَابَةٍ لَمْ يُصِبْهَا الْمَاءُ فُعِلَ بِهِ كَذَا وَكَذَا مِنَ النَّارِ قَالَ عَلِيٌّ فَمِنْ ثَمَّ عَادَيْتُ رَأْسِي قَالَ قَالَ عَبْدُ اللهِ فِي حَدِيثِهِ وَكَانَ يَجُزُّ شَعْرَهُ

"مَنْ تَرَكَ مَوْضِعَ شَعْرَةٍ مِن جَسَدِه مِنْ جَنَابَة لَمْ يَغْسِلها فُعِلَ بها كذَا وكذَا من النار".

"عَنْ زَاذَانَ، عَنْ عَلِىٍّ: أَنَّ رَسُولَ الله ﷺ قَالَ: مَنْ تَرَكَ مَوْضِعَ شَعْرَةٍ مِنْ جَسَدِهِ مِنْ جَنَابَةٍ لَمْ يَغْسِلْهُ فُعِلَ بِهِ كَذَا وَكَذَا فِى النَّارِ، قَالَ عَلِىٌّ: فَمِنْ ثَمَّ عَارَيْتُ شَعْرِى، وَكَانَ يَجُزُّ شَعَرهُ".