Sahih Muslim 1690
صحيح مسلم#1690SahihAbu Huraira reported that the Messenger of Allah (ﷺ) recited in the two (supererogatory) rak'ahs of the dawn (prayer):" Say: O unbelievers," (Qur'an, cix.) and" Say: Allah is one" (cxii)
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: 6:120