Sahih Muslim 1286
صحيح مسلم#1286SahihAbdullah b. Mas'ud reported:The Apostle of Allah (ﷺ) performed two prostrations for forgetfulness after salutation and talking
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: 5:124