Sahih Muslim 1892
صحيح مسلم#1892SahihUqba b. 'Amir reported:The Messenger of Allah (ﷺ) said to me: There have been sent down to me verses the like of which had never been seen before. They are the Mu'awwadhatain
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: 6:320