A person is approached [by the angels of punishment] in the grave from the legs then the legs say: �You cannot approach him from here for he used to stand on us reciting Surat al-Mulk�; when they approach his chest it says: �You cannot approach him from here for he preserved Surat al-Mulk in me�; and when they approach his head it says: �You cannot approach him from here for he used to recite Surat al-Mulk with me.� Hence this Sura is the Immunizer (al-Mani`a), it immunizes one from the punishment of the grave. It is mentioned in the Torah as Surat al-Mulk also. If anyone recites it in the night he has accomplished a great deal and has excelled!
***Warning on Companion-sayings that concern the unseen (ghayb)***
It is narrated from Ibn Mas`ud (Allah be well-pleased with him and reward and thank him!) as his saying but has the probative force of a hadith of the Prophet, upon him blessings and peace, because it relates news of unseen matters in which there is no room for opinion, therefore Ibn Mas`ud necessarily heard it from the Prophet, upon him blessings and peace.