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.
Sunan Abi Dawud Book 1, Hadith 297
← Previous Hadith I said: Messenger of Allah, Fatimah daughter of Abu Hubaish had a flow of blood for a certain period and did not pray. The Messenger of Allah (ﷺ) said: Glory be to Allah! This comes from the devil. She should sit in a tub, and when she sees yellowness of the top of the water, she would take a bath once for the Zuhr and 'Asr prayer, and take another bath for the Maghrib and 'Isha prayers, and take a bath once for the fajr prayer, and in between times she would perform ablution.

Abu Dawud said: Mujahid reported on the authority of Ibn 'Abbas: When bathing became hard for her, he commanded her to combine the two prayers.

Abu Dawud said: Ibrahim reported it from Ibn 'Abbas. This is also the view of Ibrahim al-Nakha'i and 'Abd Allah b. Shaddad.

Sunan Abi Dawud Book 1, Hadith 296 Next Hadith → 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.

Sunan Abi Dawud Book 1, Hadith 298