The Messenger of Allah ﷺ said: There is sexual defilement under every hair; so wash the hair and cleanse the skin. Abu Dawud said: The tradition narrated by Harith b. Wajih is rejected (Munkar). He is weak (in transmission).
قَالَ رَسُولُ اللَّهِ ﷺ إِنَّ تَحْتَ كُلِّ شَعْرَةٍ جَنَابَةً فَاغْسِلُوا الشَّعْرَ وَأَنْقُوا الْبَشَرَ
the Prophet said: "Under every hair is sexual impurity so wash (all of) the hair and cleanse the skin."
عَنِ النَّبِيِّ ﷺ قَالَ تَحْتَ كُلِّ شَعْرَةٍ جَنَابَةٌ فَاغْسِلُوا الشَّعَرَ وَأَنْقُوا الْبَشَرَ قَالَ وَفِي الْبَابِ عَنْ عَلِيٍّ وَأَنَسٍ
"The Messenger of Allah said: 'Under every hair there is the state of sexual impurity, so wash the hair and cleanse the skin.'"
قَالَ رَسُولُ اللَّهِ ﷺ إِنَّ تَحْتَ كُلِّ شَعَرَةٍ جَنَابَةً فَاغْسِلُوا الشَّعَرَ وَأَنْقُوا الْبَشَرَةَ
"تَحْتَ كُلِّ شَعْرَة جَنَابَة، فَبُلُّوا الشعْرَ، وأنْقُوا البَشَرَةَ" .
"إِنَّ تحْتَ كلِّ شَعْرةٍ جَنابةً، فَاغْسِلوا الشَّعْر، وأَنْقُوا الْبَشْرَةَ" .