Sahih Muslim 1548
صحيح مسلم#1548SahihAnas b. Malik reported that the Messenger of Allah (ﷺ) observed Qunut for a month in the dawn prayer after ruku' and invoked curse upon Bani Usayya
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: 5:381