The Virtues of Reciting Surah Al Mulk Every Night
‘Abdullaah ibn Mas'ood (radhiAllahu 'anhu) said:

“Whoever reads 'al-Mulk’ every night, Allaah will protect him from the torment of the grave. At the time of the Messenger of Allaah (sallAllahu 'alayhi wa sallam), we used to call it al-mani'ah (that which protects). In the Book of Allah, there is a chapter [and] whoever recites it every night has done very well.”

[Sahih at-Targhib wat-Tarhib, no. 1475]

Imam Ahmad recorded from Abu Hurayrah (may Allah be pleased with him) that Allah’s Messenger (sallAllahu 'alayhi wa sallam) said,

“Verily, there is a chapter in the Qur'an which contains thirty Ayat that will intercede on behalf of its reciter until he is forgiven. (It is): 'Blessed be He in Whose Hand is the dominion.’”

[This Hadith was collected by At-Tirmidhi and the four Sunan Compilers. ”]

He (sallAllahu 'alayhi wa sallam) used to recite Surah As-Sajdah and Surah Al-Mulk (in Arabic) before sleeping.

[Reference: At-Tirmithi, An-Nasa'i. See also Al-Albani, Sahihul-Jami ’ As-Saghir 4/255]

Abu Hurairah (may Allah be pleased with him) reported: I heard the Messenger of Allah (sallAllahu 'alayhi wasallam) 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]