Sahih Muslim 1687
صحيح مسلم#1687SahihA'isha reported:I have never seen the Messenger of Allah (ﷺ) hastening as much in observing supererogatory as two rak'ahs before the (Fard) of the dawn prayer
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: 6:117