Fatimah bint Abi Hubaish came to the Messenger of Allah ﷺ and said: "I am a woman who suffers from Istihadah and I never become pure. Should I stop praying?" He said: "No, that is a vein, it is not menstruation. When your period comes, stop praying, and when it goes, wash the blood from yourself and pray."
جَاءَتْ فَاطِمَةُ بِنْتُ أَبِي حُبَيْشٍ إِلَى رَسُولِ اللَّهِ ﷺ فَقَالَتْ إِنِّي امْرَأَةٌ أُسْتَحَاضُ فَلاَ أَطْهُرُ أَفَأَدَعُ الصَّلاَةَ قَالَ لاَ إِنَّمَا ذَلِكِ عِرْقٌ وَلَيْسَتْ بِالْحِيضَةِ فَإِذَا أَقْبَلَتِ الْحِيضَةُ فَدَعِي الصَّلاَةَ وَإِذَا أَدْبَرَتْ فَاغْسِلِي عَنْكِ الدَّمَ وَصَلِّي