Anas ibn Malik reported: The Messenger of Allah, peace and blessings be upon him, said, “There is a chapter in the Quran, not but thirty verses, which will argue on behalf of its companion until he enters Paradise. It is the chapter: Blessed is He in whose hand is the dominion.” (67:1, surat Al Mulk))
Source: al-Mu’jam al-Awsaṭ 3667
Grade: Hasan (fair) according to Al-Albani

From this Hadith, it’s says the benefit of reciting Surah Mulk is likened to a companion. These these thirty verses will serve us like a intimate relationship of a friend which will vouch for your (intercede) and ask for forgiveness on your behalf. (myislam.org)