Sahih Muslim 759
صحيح مسلم#759SahihOn the authority of 'A'isha:Umm Habiba asked the Messenger of Allah (ﷺ) about the blood (which flows beyond the period of menstruation). 'A'isha said: I saw her wash-tub full of blood. The Messenger of Allah (ﷺ) said: Remain away (from prayer) equal (to the length of time) that your menses prevented you. After this (after the period of usual courses) bathe yourself and offer prayer
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 3:81