She used to experience prolonged bleeding, so the Prophet ﷺ said to her, "When it is menstrual blood, it is black and recognizable, so when that occurs, refrain from prayer. But when it is the other kind, perform ablution and pray, for it is only from a vein."
أنها كانت تستحاض، فقال لها النبي ﷺ: إذا كان دم الحيضة- فإنه دم أسود يعرف- فإذا كان ذلك فأمسكي عن الصلاة، فإذا كان الآخر فتوضئي وصلي؛ فإنما هو عرق.
Abu Dawud (286) narrated it, saying, Muhammad bin Muthanna told us, Muhammad bin Abu Adi told us, from Muhammad, meaning Ibn Amr, who said, Ibn Shihab told me, from Urwa bin Zubayr, from Fatimah bint Abu Hubaysh, and he related the hadith.Abu Dawud said, Ibn Muthanna said, Ibn Abu Adi narrated it to us from his book in this manner, then he later narrated it to us from memory, saying, Muhammad bin Amr told us, from Zuhri, from Urwa, from Ayesha, that Fatimah used to experience prolonged bleeding, and he related its meaning. So the hadith goes back to being from the musnad of Ayesha.Its chain of transmission is hasan on account of Muhammad bin Amr bin Alqama, for his hadith is hasan when he does not err. These hadiths reinforce one another, and the majority of the scholars, including Shafii, Ahmad, Abu Thawr, and others, relied on them to conclude that a woman with prolonged bleeding should perform wudu before every prayer. Abu Hanifa said that her state of purity is determined by a fixed period of time, so she may combine two or more obligatory prayers with a single wudu, and pray as many voluntary prayers as she wishes, until something occurs that breaks her wudu.