Ibne-'Abbas Radiyallahu 'anhuma narrates that someone, amongst the companions of Nabi Sallallahu 'alaihi wasallam, set up his tent over a grave, without realizing that it was a grave. Suddenly he heard the person of the grave reciting Surah Mulk, up to its end of the Surah. He came to Nabi Sallallahu 'alaihi wasallam and said: O Rasullallah I set up my tent unknowingly over a grave, and suddenly I heard someone reciting Surah Mulk up to its end. Nabi Sallallahu 'alaihi wasallam said: It is the defender; it is the protector which safeguards him from the Punishment in the grave. (Tirmidhi: 2890)