Da'if
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا الأَسْوَدُ بْنُ عَامِرٍ، حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، عَنْ عَطَاءِ بْنِ السَّائِبِ، عَنْ زَاذَانَ، عَنْ عَلِيِّ بْنِ أَبِي طَالِبٍ، عَنِ النَّبِيِّ ـ صلى الله عليه وسلم ـ 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 .
It was narrated from 'Ali bin Abu Talib that: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