Sahih Muslim 6741
صحيح مسلم#6741SahihSahl b. Sa'd reported it from Allah's Messenger (ﷺ) that a person performs deeds like the deeds of the people of Paradise apparently before people and he would be amongst the dwellers of Hell and a person acts apparently like the people of Hell, but (in fact) he would be among the dwellers of Paradise
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: 46:19