“Sa'd said: ‘I had seen the Prophet (Allah bless him and give him peace) laugh at the Battle of the Trench, so hard that his molar teeth became apparent.’ I said: ‘How was his laughter?’ He said: ‘There was a man holding a shield while Sa'd was shooting, and the man was saying such-and-such and such-and-such, with the shield covering his forehead. Sa'd therefore aimed an arrow at him and shot it when he raised his head, so it did not miss this part of him — meaning his forehead — and the man toppled over and kicked up his foot. The Prophet (Allah bless him and give him peace) then laughed so much that his molar teeth became apparent.’ I asked: ‘What made him laugh?’ He replied: ‘What he did to the man!”
"I was present when 'Ali (may Allah be well pleased with him) had an animal brought for him to ride. When he placed his foot in the stirrup, he said: “In the Name of Allah . (Al-Qur'an;43:13-14)Then he said: “Praise be to Allah,” three times, and: “Allah is Supremely Great,” three times, then: “Glory be to You! I have wronged myself, so forgive me, for no one forgives sins but You!” Then he laughed, so I said to him: “What has made you laugh, O Commander of the Believers?” He said: “I saw Allah’s Messenger (Allah bless him and give him peace) do just as I did now, after which he laughed, so I said: "What has made you laugh, O Messenger of Allah?" He replied: ‘Your Lord surely marvels at His servant when he says: “My Lord, forgive me my sins,
knowing that no one but He forgives sins'!”
Narrated Abdullah ibn Mas'ud said (may Allah be well pleased with him):
"Allah’s Messenger said (Allah bless him and give him peace): “I am well aware of the last person to emerge from the Hellfire. After crawling out, he will be told: ‘Go and enter the Garden of Paradise!’ He will therefore enter the Garden of Paradise, but he will find that the people have occupied the abodes, so he will return and say: ‘O my Lord, the people have occupied the abodes!’ He will therefore be asked: ‘Do you remember the time you were in?’ He will say: ‘Yes,’ so he will be told: ‘Make a wish!’ He will make a wish, whereupon he will be told: ‘You have what you wished for, and this world ten times over!’ He will then say: ‘Are you, the Sovereign, mocking me?”’ He said: “I saw Allah’s Messenger (Allah bless him and give him peace) grin so broadly that his molar teeth showed!”