Fatima bint Abi Hubaish came to the Prophet ﷺ and said, "O Messenger of Allah ﷺ I get persistent bleeding from the uterus and do not become clean. Shall I give up my prayers?" Messenger of Allah ﷺ replied, "No, because it is from a blood vessel and not the menses. So when your real menses begins give up your prayers and when it has finished wash off the blood (take a bath) and offer your prayers." Hisham (the sub narrator) narrated that his father had also said, (the Prophet ﷺ told her): "Perform ablution for every prayer till the time of the next period comes." (Using translation from Bukhārī 228)
جَاءَتْ فَاطِمَةُ بِنْتُ أَبِي حُبَيْشٍ إِلَى رَسُولِ اللهِ ﷺ فَقَالَتْ يَا رَسُولَ اللهِ إِنِّي امْرَأَةٌ أُسْتَحَاضُ فَلَا أَطْهُرُ أَفَأَدَعُ الصَّلَاةَ؟ فَقَالَ لَا إِنَّمَا ذَلِكَ عِرْقٌ وَلَيْسَ بِالْحَيْضِ فَإِذَا أَقْبَلَتْ حَيْضَتُكِ فَدَعِي الصَّلَاةَ وَإِذَا أَدْبَرَتْ فَاغْسِلِي عَنْكِ الدَّمَ ثُمَّ صَلِّي قَالَ قَالَ أَبِي ثُمَّ تَوَضَّئِي لِكُلِّ صَلَاةٍ حَتَّى يَجِيءَ ذَلِكَ الْوَقْتُ