(63) باب غَسْلِ الدَّمِ
Narrated `Aisha:
Fatima bint Abi Hubaish came to the Prophet (ﷺ) and said, "O Allah's Messenger (ﷺ) I get persistent bleeding from the uterus and do not become clean. Shall I give up my prayers?" Allah's Messenger (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."
Reference: Sahih al-Bukhari 228
In-book reference: Book 4, Hadith 95
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 4, Hadith 228