"Fatimah bint Abi Hubaish came to the Prophet: 'O Messenger of Allah! I am a woman who bleeds continuously and never becomes pure. Should I give up prayer?' he said: 'No, that is just a vein and is not menstruation. Do not perform prayer during the days of your period, then take a bath, and perform ablution for each prayer, even if drops of blood fall on the mat.'"  

جَاءَتْ فَاطِمَةُ بِنْتُ أَبِي حُبَيْشٍ إِلَى النَّبِيِّ ﷺ فَقَالَتْ يَا رَسُولَ اللَّهِ إِنِّي امْرَأَةٌ أُسْتَحَاضُ فَلاَ أَطْهُرُ أَفَأَدَعُ الصَّلاَةَ قَالَ لاَ إِنَّمَا ذَلِكَ عِرْقٌ وَلَيْسَ بِالْحَيْضَةِ اجْتَنِبِي الصَّلاَةَ أَيَّامَ مَحِيضِكِ ثُمَّ اغْتَسِلِي وَتَوَضَّئِي لِكُلِّ صَلاَةٍ وَإِنْ قَطَرَ الدَّمُ عَلَى الْحَصِيرِ