English Translation of Hadith
Hazrat Anas bin Malik (May Allah be pleased with him) reported: Messenger of Allah [SAWW](PBUH) delivered a Khutbah to us the like of which I had never heard from him before. He said, "If you knew what I know, you would laugh little and weep much". Thereupon those present covered their faces and began sobbing.
[Al-Bukhari Volume 8, Book 76, Hadith # 493].
Another narration is: Messenger of Allah [SAWW](PBUH) heard of something about his Companions upon which he addressed them and said, "Jannah and (Hell) Fire were shown to me and I have never seen the like of this day in good and in evil. If you were to know what I know, you would laugh little and weep much". His Companions experienced such suffering on that day that had no equal. They covered their faces and began to weep. [Al-Bukhari].
Lesson : as mentioned above in Surah Ar-Rum [The Romans] Ayat 26. “whatever is in the heavens and the earth. All are obedient to Him” We learn from this Hadith that Jannah and Hell do exist. The Prophet (PBUH) was shown both of them. 2. Excessive laughing is improper because it indicates that one is careless and forgetful of the Hereafter, while a Muslim is required to be all the time alert and careful about it. 3. To weep out of fear of Allah, is praiseworthy because it indicates that one’s heart is full of fear and he is worried about the Hereafter.