Sahih al-Bukhari 326
صحيح البخاري#326SahihNarrated Um `Atiya:We never considered yellowish discharge as a thing of importance (as menses)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 6:31