Sahih Muslim 2612
صحيح مسلم#2612SahihJabir b. 'Abdullah (Allah be pleased with both of them) reported that in the course of a journey Allah's Messenger (ﷺ) saw a man, people crowding around him and providing him a shade. Upon this he (the Holy Prophet) said:What is the matter with him? They said: He is a person observing fast. Whereupon the Messenger of Allah (ﷺ) said: It is no righteousness that you fast on journey
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: 13:118