Sahih Muslim 1672
صحيح مسلم#1672SahihAbu Huraira reported. My friend (the Holy Prophet, may peace be upon him) has instructed me to do three things:three fasts during every month, two rak'ahs of the forenoon prayer, and observing Witr prayer before going to bed
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: 6:102