المعنى الاصطلاحي :

Questioning of the dead in the grave by two angels who ask: who is your Lord, your religion, and your prophet?

الشرح المختصر :

Belief in "Fitnat al-Qabr" (trial of the grave) is part of the belief in the afterlife. It is a trial of the dead by two angels. When the soul departs the body at death and one is put in the grave, this marks the first stage of the afterlife. Two angels, named Munkar and Nakeer, are assigned for interrogating the dead. They make him sit in the grave and ask him about the Oneness of Allah and the message of the prophet: Who is your Lord? What is your religion? Who is your Prophet? If he answers them, that is good for him. If he does not answer them, they beat him severely. "Fitnat al-Qabr" is true according to Ahl-us-Sunnah wa al-Jamā‘ah. It affects the soul and the body, being the last trial that the believer will go through. "Fitnat al-Qabr" happens to every dead person, Muslim and non-Muslim alike, from the nation of Prophet Muhammad (all human beings from the time of the Prophet Mohammad until the end of the world) and from the previous nations. It does not matter whether, after death, one is buried in the earth, thrown in the sea, eaten by carnivorous animals, or burned, interrogation is inevitable. The grave, here, means the place where the dead is buried after death.