It was narrated that Anas bin Malik said: "The Messenger of Allah (ﷺ) led us in prayer one day, then he turned to face us and said: “I am now your imam, so do not hasten to bow or prostrate or stand or leave before I do. I can see you in front of me and behind me.' Then he said: “By the One in Whose Hand is my soul, if you had seen what I have seen, you would laugh little and weep much.' We said: “What have you seen, O Messenger of Allah (ﷺ)?' He said: “Paradise and Hell””””"
SahihSahihSahih MuslimBook 13 · Hadith 185