Umm Habibah daughter of Jahsh had a prolonged flow of blood. The Prophet ﷺ commander her to refrain (from prayer) during her menstrual period; then she should wash and pray. If she sees anything (which renders ablution void) she should perform ablution and pray. Abu Dawud said: This is the view held by Malik b. Anas.
أَنَّهُ كَانَ لاَ يَرَى عَلَى الْمُسْتَحَاضَةِ وُضُوءًا عِنْدَ كُلِّ صَلاَةٍ إِلاَّ أَنْ يُصِيبَهَا حَدَثٌ غَيْرُ الدَّمِ فَتَوَضَّأُ