Jāmiʿ at-Tirmidhī 2596

The full narration

Abu Dharr narrated that the Messenger of Allah (s.a.w) said:" I know the last of the people of the Fire to depart from the Fire and the last of the people of Paradise to enter Paradise. A man will be brought forth and He (s.a.w) will say: 'Ask about his small sins and hide his large sins.' So it will be said to him: 'Did you do this and that on such and such a day, did you do this and that on such- and – such a day?'” He said: “Then it will be said to him; 'For each of your sins you shall have a reward.'” He (s.a.w) said: “So he will say: 'O Lord! I have done things that I do not see here.'” He (Abu Dharr) said: “I saw the Messenger of Allah (s.a.w) laugh until his molars were visible.” (Sahih)