Question: Is it true to call death a dream and the torment in the grave a nightmare?
No, it is very wrong. Death is a blessing for a Believer and a calamity for a disbeliever. Allahu taālā said to Azrāil alaihis-salām, Take the souls of My friends with ease and those of My enemies with difficulty.
It was declared in a hadīth-i sharīf:
(At the time of death, a Believer sees the Angels of Compassion, so he does not feel the pangs of death. His soul leaves him with utter ease, and he attains blessings.) [Bazzār]
At that moment, a Believer becomes very happy. Hadrat Azrāīl says to such a Believer, Dont be afraid. You are going to the Arhamurrāhimīn (the Most Compassionate of the compassionate). You are arriving in your own home. You are attaining to a great fortune. For such a person there is no other day more honored than this. A Believers soul leaving his or her body, that is, his or her dying, is like the emancipation of a slave from prison. It was declared in a hadīth-i sharīf:
(Death is the most valuable gift for a Believer.) [Tabarānī]
To die does not mean a dream. To die does not mean to cease to exist, either. It is an event that does not annihilate existence. Death is the termination of the souls attachment to the body. It is an act of the soul leaving the body. Death is a matter of humans changing from one state into another. It is to migrate from one home to another. A Believer who wants to attain to Allahu taālā does not regard death as evil because death is a bridge that leads a lover to his beloved. A person who loves Paradise and prepares himself or herself for Paradise loves death, for Paradise is inaccessible without death.
The life of the world is like a dream. With the awakening of death, the dream will be over, the real life will commence. It was stated in a hadīth-i sharīf, Humans are asleep. They will wake up when they are dead (Safar-i ākhirat).
The torment in the grave is not a nightmare but the real torment. These facts were clearly stated in hadīth-i sharīfs. After death, the souls of Believers attain blessings while those of disbelievers are subjected to torment. A hadīth-i sharīf says, The grave is either a garden of Paradise or a pit of Hell (Tirmidhī).
Humans are asleep
Question: Are prophets, too, included in the hadīth Humans are asleep?
Prophets and friends of Allahu taālā had died before they [physically] died, attained the blessings to be given in the Hereafter, and woke up from heedlessness (ghaflah) in the world.