Sahih Muslim 1466
صحيح مسلم#1466SahihAbu Dharr reported:The Messenger of Allah (ﷺ) said to me: O Abu Dharr, you would soon find after me rulers who would make their prayers dead. You should say prayer at its prescribed time. If you say prayer at its prescribed time that would be a supererogatory prayer for you, otherwise you saved your 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: 5:299