Imam Ahmad recorded that Abu Sa`id said that the Messenger of Allah Sallahu Alayhi wa Sallam said,
When the people of Paradise enter Paradise and the people of the Hellfire enter the Hellfire, death will be brought in the form of a handsome ram and it will be placed between Paradise and the Hellfire. Then, it will be said, “O people of Paradise, do you know what this is?” Then, they will turn their gazes and look, and they will say, “Yes, this is death.”
Then, it will be said, “O people of the Hell fire, do you know what this is?” Then, they will turn their gazes and look, and they will say, “Yes, this is death.” Then, the order will be given for it to be slaughtered and it will be said, “O people of Paradise, eternity and no more death, O people of Hellfire, eternity and no more death.”
Then the Messenger of Allah recited this Ayah: “And warn them of the Day of grief and regret, when the case has been decided, while (now) they are in a state of carelessness, and they believe not.”
Then, the Messenger of Allah made a gesture with his hand and said, “The people of this life are in the state of heedlessness of this life.”
(Thus recorded Imam Ahmad and it was also recorded by Al-Bukhari and Muslim in their Sahihs with wording similar to this.)
It is reported from Abdullah bin Mas`ud that he mentioned a story in which he said,
“There is not a soul except that it will see a residence in Paradise and a residence in the Hellfire, and this will be the Day of distress. So the people of the Hellfire will see the residence that Allah prepared for them if they had believed. Then, it will be said to them, “If you had believed and worked righteous deeds, you would have had this, which you see in Paradise.” Then, they will be overcome with distress and grief. Likewise, the people of Paradise will see the residence that is in the Hellfire and it will be said to them, “If Allah had not bestowed His favor upon you (this would have been your place).”