In Sermon 20 of Nahjul Balaghah, the first Shia Imam, Ali ibn Abitaleb (AS) said: If you could see what dead ones saw, you would be impatient and frightened; and you could hear and obey. But whatever they can see it is covered for you and it is near for curtains to fall down. Imam Ali (AS) continued: The truth has been shown to the human being in the world; if you look properly, and listen to the voice of the truth, admonitory examples can be seen by all the human beings in this world. Imam Ali (AS) added: The Day of Judgement is ahead of you and death behind you to steer you; unburden yourselves to arrive. Indeed, those who have gone are waiting for you.
source:shafaqna