Fatimah b. Abu Hubaish came to the Apostle ﷺ and said: I am a woman whose blood keeps flowing (even after the menstruation period). I am never purified; should I, therefore, abandon prayer? He (the Holy Prophet) said: Not at all, for that is only a vein, and is not a menstruation, so when menstruation comes, abandon prayer, and when it ends wash the blood from yourself and then pray. (Using translation from Muslim 333a)
قَالَتْ فَاطِمَةُ بِنْتُ أَبِي حُبَيْشٍ يَا رَسُولَ اللهِ إِنِّي امْرَأَةٌ أُسْتَحَاضُ فَلَا أَطْهُرُ أَفَأَدَعُ الصَّلَاةَ؟ فَقَالَ النَّبِيُّ ﷺ «إِنَّمَا ذَلِكَ عِرْقٌ وَلَيْسَ بِالْحَيْضَةِ فَإِذا أَقْبَلَتِ الْحَيْضَةُ فَدَعِي الصَّلَاةَ وَإِذَا أَدْبَرَتْ فَاغْتَسِلِي عَنْكِ الدَّمَ ثُمَّ صَلِّي»