The Prophet ﷺ said about the woman having a prolonged flow of blood: She should abandon prayer during her menstrual period: then she should take a bath and pray. She should perform ablution for every prayer. Abu Dawud said: 'Uthman added: She should keep fast and pray.  

عَنِ النَّبِيِّ ﷺ فِي الْمُسْتَحَاضَةِ تَدَعُ الصَّلاَةَ أَيَّامَ أَقْرَائِهَا ثُمَّ تَغْتَسِلُ وَتُصَلِّي وَالْوُضُوءُ عِنْدَ كُلِّ صَلاَةٍ  

Fatimah daughter of AbuHubaysh came to the Prophet ﷺ and narrated what happened with her. He said: Then take a bath and then perform ablution for every prayer and pray.  

جَاءَتْ فَاطِمَةُ بِنْتُ أَبِي حُبَيْشٍ إِلَى النَّبِيِّ ﷺ فَذَكَرَ خَبَرَهَا وَقَالَ ثُمَّ اغْتَسِلِي ثُمَّ تَوَضَّئِي لِكُلِّ صَلاَةٍ وَصَلِّي  

She should take bath, i.e. only once; then she should perform ablution until he next menstrual period.  

عَنْ عَائِشَةَ فِي الْمُسْتَحَاضَةِ تَغْتَسِلُ تَعْنِي مَرَّةً وَاحِدَةً ثُمَّ تَوَضَّأُ إِلَى أَيَّامِ أَقْرَائِهَا  

All the traditions (on this subject) transmitted by 'Adi b. Thabit and A'mash on the authority of Habib and Ayyub al-'Ala, all of them are weak; none of them is sound. This tradition indicates the tradition reported by al-A'mash a a statement of Companion, i.e. 'Aishah. Hafs b. Ghayath has rejected the tradition transmitted by Habib as the statement (of the Prophet). And Asbat also reported it as a statement of 'Aishah. Abu Dawud said: Ibn Dawud has narrated the first part of this tradition as a statement (of the Prophet), and denied that there was any mention of performing ablution for every prayer. The weakness of the tradition reported by Habib is also indicated by the fact that the version transmuted by al-Zuhri from 'Urwah on the authority of 'Aishah says that she used to wash herself for every prayer; (these words occur) in the tradition about the woman who has a flow of blood. This tradition has been reported by Abu al-Yaqzan from 'Adi b. Thabit from his father from 'Ali, and narrated by 'Ammar, the freed salve of Banu Hashim, from Ibn 'Abbas, and transmitted by 'Abd al-Malik b. Maisarah, Bayan, al-Mughirah, Firas, on the authority of al-Sha'bi, from Qumair from 'Aishah, stating: You should perform ablution for every prayer. The version transmitted by Dawud, and 'Asim from al-Sha'bi from Qumair from 'Aishah has the words: She should take bath only once every day. The version reported by Hisham b. 'Urwah from his father has the words: The woman having a flow of blood should perform ablution for every prayer. All these traditions are weak except the tradition reported by Qumair and the tradition reported by 'Ammar, the freed slave of Banu Hashim, and the tradition narrated by Hisham b. 'Urwah on the authority of his father. What is commonly known from Ibn 'Abbas is bathing (for every prayer).  

عَنِ النَّبِيِّ ﷺ مِثْلَهُ