Fatimah daughter of Abu Hubaish came to the Messenger of Allah ﷺ and said: I am a woman who has prolonged flow of blood; I am never purified ; should I abandon prayer ? He replied: This is (due to) a vein, and not menstruation. When the menstruation begins, you should abandon prayer ; when it is finished, you should wash away the blood and pray. (Using translation from Abū Dāʾūd 282)
جَاءَتْ فَاطِمَةُ بِنْتُ أَبِي حُبَيْشٍ إِلَى رَسُولِ اللهِ ﷺ فَقَالَتْ إِنِّي مُسْتَحَاضَةٌ فَلَا أَطْهُرُ أَفَأَدَعُ الصَّلَاةَ؟ قَالَ لَا إِنَّمَا ذَلِكَ عِرْقٌ وَلَيْسَ بِالْحَيْضِ فَإِذَا أَقْبَلَتِ الْحَيْضَةُ فَدَعِي الصَّلَاةَ وَإِذَا أَدْبَرَتْ فَاغْسِلِي عَنْكِ الدَّمَ وَصَلِّي أَخْرَجَاهُ مِنْ حَدِيثِ هِشَامِ بْنِ عُرْوَةَ فِي الصَّحِيحِ