Believing in the hereafter and the reward and punishment in it is one of the fundamentals of islam.Allah made signs before it indicating its approach.The prophet made the matter of the hereafter great ,whenever he mentioned it his voice became louder and he got angery.Due the prophet’s repetition of the Hour the companions feared that it might have taken place during their life .
They used to sit discussing it as narrated by Huzaifa that the prophet came while they were having discussion.He asked them:" what are you having discussion about?’’ They answered: ’’About The Hour’’.