Sunan an Nasai
1363
Sahih+2

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

SahihAbu Ghuddah
SahihAl-Albani