Anas bin Malik (May Allah be pleased with him) reported:

Messenger of Allah (ﷺ) 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. <b>[Al-Bukhari and Muslim]</b>. Another narration is: Messenger of Allah (ﷺ) 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.

وعن أنس، رضي الله عنه، قال‏:‏ خطبنا رسول الله، صلى الله عليه وسلم خطبة ما سمعت مثلها قط، فقال‏:‏ ‏"‏لو تعلمون ما أعلم لضحكتم قليلاً ولبكيتم كثيراً‏"‏ فغطى أصحاب رسول الله، صلى الله عليه وسلم وجوههم، ولهم خنين‏.‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏ ‏.‏ وفي رواية‏:‏ بلغ رسول الله، صلى الله عليه وسلم عن أصحابه شئ فخطب ، فقال‏:‏ ‏"‏عرضت على الجنة والنار، فلم أر كاليوم في الخير والشر، ولو تعلمون ما أعلم لضحكتم قليلا، ولبكيتم كثيراً‏"‏ فما أتى على أصحاب رسول الله، صلى الله عليه وسلم يوم أشد منه، غطوا رؤوسهم ولهم خنين‏.‏