Hadith: Paradise and Hell were presented to me, and I have never seen good and evil like what I saw today. If you knew what I know, you will rarely laugh and you will cry abundantly

عن أنس رضي الله عنه قال: خَطَبَنَا رسولُ اللهِ صلى الله عليه وسلم خُطْبَةً ما سمعتُ مثلها قَطُّ، فقال: «لو تَعْلَمُونَ ما أَعْلَمُ، لَضَحِكْتُمْ قَلِيلًا وَلَبَكَيْتُمْ كَثِيرًا». فَغَطَّى أَصْحَابُ رسولِ اللهِ صلى الله عليه وسلم وُجُوهَهُم، ولهم خَنِينٌ. وفي رواية: بَلَغَ رسولَ اللهِ صلى الله عليه وسلم عن أَصْحَابِهِ شَيْءٌ فَخَطَبَ، فقال: «عُرِضَتْ عَلَيَّ الجَنَّةُ والنَّارُ، فَلَمْ أَرَ كاليومِ في الخيرِ والشرِ، ولو تَعْلَمُونَ ما أَعْلَمُ لَضَحِكْتُمْ قَلِيلًا وَلَبَكَيْتُمْ كَثِيرًا». فما أَتَى على أصحابِ رسولِ اللهِ صلى الله عليه وسلم يومٌ أَشَدُّ مِنْهُ، غَطَّوا رُءُوسَهُمْ ولهم خَنِينٌ.
[صحيح] - [متفق عليه]

Anas (may Allah be pleased with him) reported: 'The Messenger of Allah (may Allah's peace and blessings be upon him) gave us a speech the like of which I never heard before. He said: "Paradise and Hellfire were presented to me, and I have never seen good and evil like what I saw today. If you knew what I know, you will rarely laugh and you will cry abundantly." In another narration: ''The Messenger of Allah was told of something about his Companions. So he gave a speech, in which he said: Paradise and Hell were presented to me, and I have never seen good and evil like what I saw today. If you knew what I know, you will rarely laugh and you will cry abundantly." The Companions had never had a harder day. They covered their heads, crying and sobbing.''
[Authentic hadith] - [Narrated by Bukhari & Muslim]

Explanation

The Prophet (may Allah's peace and blessings be upon him) gave his Companions an admonishment that they never heard before. He told them that Paradise and Hellfire were presented to him, and he never saw of details of good and evil as he saw that day. He also said that if they knew what he knew about the major events of the afterlife, including the bliss of Paradise and the torment of Hellfire they would rarely laugh and cry abundantly and profusely. The Companions had never a harder day; they wept severely.