Sahih al-Bukhari 327
Sahih al-Bukhari · Book 6: Menstrual Periods · Al-Istihadah (bleeding in between the periods is from a blood vessel)
Narrated `Aisha:
حَدَّثَنَا إِبْرَاهِيمُ بْنُ الْمُنْذِرِ ، قَالَ حَدَّثَنَا مَعْنٌ ، قَالَ حَدَّثَنِي ابْنُ أَبِي ذِئْبٍ ، عَنِ ابْنِ شِهَابٍ ، عَنْ عُرْوَةَ ، وَعَنْ عَمْرَةَ ، عَنْ عَائِشَةَ ، زَوْجِ النَّبِيِّ صلى الله عليه وسلم أَنَّ أُمَّ حَبِيبَةَ اسْتُحِيضَتْ سَبْعَ سِنِينَ، فَسَأَلَتْ رَسُولَ اللَّهِ صلى الله عليه وسلم عَنْ ذَلِكَ، فَأَمَرَهَا أَنْ تَغْتَسِلَ فَقَالَ " هَذَا عِرْقٌ " . فَكَانَتْ تَغْتَسِلُ لِكُلِّ صَلاَةٍ .
(the wife of the Prophet) Um Habiba got bleeding in between the periods for seven years. She asked Allah's Messenger (ﷺ) about it. He ordered her to take a bath (after the termination of actual periods) and added that it was (from) a blood vessel. So she used to take a bath for every prayer.