Sahih Muslim 1556
صحيح مسلم#1556SahihAl-Bari' reported that the Messenger of Allah (ﷺ) observed Qunut in the dawn and evening (prayers)
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: 5:389