عَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا قَالَتْ: أَجْمَرْتُ رَأْسِي إِجْمَارًا شَدِيدًا فَقَالَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ: ((يَا عَائِشَةُ! أَمَا عَلِمْتِ أَنَّ عَلَى كُلِّ شَعْرَةٍ جَنَابَةً؟))
It is narrated from Sayyida Aisha (may Allah be pleased with her), she says: I had tied my hair very tightly, the Noble Prophet (peace and blessings be upon him) said: Aisha! Do you not know that every hair becomes impure due to janabah!?