Surah Al-Mulk (meaning ‘The Sovereignty’) is the 67th chapter (Surah) of the Quran. Surah Al-Mulk has 30 verses (Ayat). Surah Al-Mulk is a Meccan Surah, a Surah that was revealed to Prophet Muhmmad ﷺ in Mecca. Like any other Surah in the Quran, Surah Al-Mulk is very important. There are many virtues from reciting this Surah.
Abu Hurairah (May Allah be pleased with him) reported:
I heard the Messenger of Allah (ﷺ) saying, “There is a Surah in the Qur’an which contains thirty Ayat which kept interceding for a man until his sins are forgiven. This Surah is ‘Blessed is He in Whose Hand is the dominion.’ (Surat Al-Mulk 67).” [At-Tirmidhi and Abu Dawud]
So as we can see from the Hadith above, Surah Al-Mulk will intercede for its reciter (the person who recites it often) on the Day of Judgement until its reciter is forgiven by Allah (SWT).
Yahya related to me from Malik from Ibn Shihab that Humayd ibn Abd ar-Rahman ibn Awf had told him that Surat al-Ikhlas (Surah 112) was equal to a third of the Qur’an, and that Surah al-Mulk (Surah 67) pleaded for its owner. [Muwatta Malik]
Narrated Ibn ‘Abbas: “One of the Companions of the Prophet (ﷺ) put up a tent upon a grave without knowing that it was a grave. When he realized that is was a person’s grave, he recited Surat Al-Mulk until its completion. Then he went to the Prophet (ﷺ) and said: ‘O Messenger of Allah (ﷺ) [Indeed] I erected my tent without realizing that it was upon a grave. So when I realized there was a person in it I recited Surat Al-Mulk until its completion.’ So the Prophet (ﷺ) said: “It (Surah Al-Mulk) is a prevention, it is a salvation delivering from the punishment of the grave.'” [Tirmidhi]
Based off the Hadith above, Surah Al-Mulk is also a prevention, and salvation delivering from the punishment of the grave.
Reading Surat al-Mulk protects a Muslim from the trials of the grave, but how often does one have to read it? Once a day or more? What is meant is that a person should read it every night, act in accordance with the rulings contained in it, and believe in the information mentioned in it.
It was narrated that ‘Abd-Allah ibn Mas’ud said: Whoever reads Tabaarak allaahi bi yadihi’l-mulk [i.e., Soorat al-Mulk] every night, Allah will protect him from the torment of the grave. At the time of the Messenger of Allah (peace and blessings of Allah be upon him) we used to call it al-maani’ah (that which protects). In the Book of Allah it is a Surah which, whoever recites it every night has done very well.
Narrated by al-Nasaa’i, 6/179; classed as hasan by al-Albaani in Saheeh al-Targheeb wa’l-Tarheeb, 1475.