Compiled by Imam Abu Dawud as-Sijistani
حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا حَمَّادٌ، أَخْبَرَنَا عَطَاءُ بْنُ السَّائِبِ، عَنْ زَاذَانَ، عَنْ عَلِيٍّ، - رضى الله عنه - أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم 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 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.