Praise be to Allah.
Soorat al-Mulk is one of the great soorahs of the Qur’an which we are encouraged in saheeh reports to recite frequently, and there are reports which say that it will protect the one who recites it from the punishment of the grave.
Abu Dawood (1400) and al-Tirmidhi (2891 – and he classed it as hasan) narrated from Abu Hurayrah that the Prophet (blessings and peace of Allah be upon him) said: “There is a soorah of the Qur’an, with thirty verses, that interceded for a man until he was forgiven; it is ‘Soorah Tabaarak Alladhi bi yadihi’l-mulk (Blessed is He in Whose Hand is the dominion)’ [al-Mulk 67:1].” It was also classed as hasan by al-Albaani in Saheeh at-Tirmidhi.
Al-Mannaawi (may Allah have mercy on him) said:
He recited it frequently, thus it kept asking Allah (to forgive him) until he was forgiven. This is encouragement to everyone to recite it regularly so as to attain its intercession.
End quote from Fayd al-Qadeer, 2/574
Shaykh ‘Abd al-Muhsin al-‘Abbaad (may Allah preserve him) said:
This hadeeth highlights its virtue and tells us that it will intercede on the Day of Resurrection for its companion, i.e., the one who recites it.
End quote from Sharh Sunan Abi Dawood, 8/7.
In the virtue mentioned, that this soorah will intercede for the one who recites it, there is nothing to limit recitation thereof to night or day; rather what may be understood from this hadeeth is that what is meant by reciting this soorah is paying particular attention to it, memorizing it, understanding it, and reciting it frequently, especially in prayer.
With regard to the report narrated by an-Nasaa’i in as-Sunan al-Kubra (10547) and in ‘Aml al-Yawm wa’l-Laylah (711), and by Abu Taahir al-Mukhliss in al-Mukhlisiyyaat (228), via ‘Arfajah ibn ‘Abd al-Waahid from ‘Aasim ibn Abi’n-Nujood from Zirr from ‘Abdullah ibn Mas‘ood, who said: “Whoever recites Soorah Tabaarak Alladhi bi yadihi’l-mulk (Blessed is He in Whose Hand is the dominion) [al-Mulk 67:1] every night, Allah will protect him thereby from the punishment of the grave”, and at the time of the Messenger of Allah (blessings and peace of Allah be upon him) we used to call it al-maani‘ah (that which protects), and that in the Book of Allah there is a soorah, everyone who recites it every night has done a great deal and has done well –
–its isnaad is layyin (weak). ‘Arfajah ibn ‘Abd al-Waahid is dubious, and no one regarded him as trustworthy. Al-Haafiz said in at-Taqreeb (389): He is acceptable, i.e., if there is any corroborating evidence, otherwise his hadeeth is layyin – as was stated in the introduction.
There is no corroborating evidence for ‘Arfajah’s version of this report with these additions. Rather he was contradicted by someone who is far more trustworthy than him, namely Sufyaan ath-Thawri. Al-Haakim (3839) narrated via Ibn al-Mubaarak, and at-Tabaraani narrated in al-Kabeer via ‘Abd ar-Razzaaq (8651), both from Sufyaan, from ‘Aasim, from Zirr, from Ibn Mas‘ood (may Allah be pleased with him) that he said: “(Angels) will come to a man in his grave; they will come to his feet and his feet will say: You have no power over us; he used to recite Soorat al-Mulk. Then they will come to his chest or his stomach and it will say: You have no power over me; he used to recite Soorat al-Mulk. Then they will come to his head and it will say: You have no power over me; he used to recite Soorat al-Mulk. So it is the maani‘ah (protector) that protects against the punishment of the grave and it is referred to in the Torah as Soorat al-Mulk, whoever recites it by night has done a great deal and has done well.
This is the correct report and it is what is known to the scholars. The words “Whoever recites it every night, Allah will protect him thereby from the punishment of the grave”, which appear in the hadeeth of ‘Arfajah, are not known to the scholars, and attribution thereof to the Prophet (sa) is also not known to them. What is correct with regard to the isnaad is that it is mawqoof (ends with the Sahaabi), as in this report of Sufyaan.
It was also narrated by Abu’sh-Shaykh in Tabaqaat al-Asbahaaniyyeen (264) in a shorter, marfoo‘ report from Ibn Mas‘ood, as follows: “Soorah Tabaarak (al-Mulk) is that which protects against the punishment of the grave.” It was narrated via Abu Ahmad az-Zubayri from Sufyaan.
Concerning Abu Ahmad az-Zubayri, Ahmad said: He made many mistakes in the hadeeth he narrated from Sufyaan. Abu Haatim said: He was a devoted worshipper and had good knowledge of hadeeth, but he made mistakes.
Tahdheeb at-Tahdheeb, 9/228
This is one of his mistakes when narrating from Sufyaan (may Allah have mercy on him). The correct report is the mawqoof report, as quoted above from Ibn al-Mubaarak and ‘Abd ar-Razzaaq.
Something similar may be said if it is deemed to be marfoo‘ (attributed to the Prophet (sa) via a complete isnaad), as was stated by more than one of the scholars. And this is in harmony with what is stated above. The hadeeth is general in meaning and it is not stipulated that it should be recited at night.
Al-Mannaawi said in at-Tayseer (2/62):
The soorah will give protection to the one who recited it; when he dies and is placed in his grave, he will not be punished there.
Abu’l-Hasan al-Mubaarakfoori (may Allah have mercy on him) said:
What is meant is that reciting this soorah in this world will be a means of salvation from the punishment of the grave.
End quote from Mar‘aat al-Mafaateeh, 7/231
According to the hadeeth of Jaabir (may Allah be pleased with him), the Prophet (blessings and peace of Allah be upon him) did not sleep until he recited Alif-Laam-Meem tanzeel (Soorat as-Sajdah) and Tabaarak alladhi bi yahihi al-mulk (Soorat al-Mulk).
Narrated by at-Tirmidhi (2892) and others; classed as saheeh by Shaykh al-Albaani (may Allah have mercy on him). However it appears to be ma‘lool (problematic), as was stated by Ibn Abi Haatim, narrating from his father, in al-‘Ilal, 1668, and ‘Ilal ad-Daaraqutni, 13/340. al-Haafiz Ibn Hajar (may Allah have mercy on him) agreed with him, as it says in Ithaaf al-Mahrah, 3/155. He also said, after discussing its isnaad: Based on that, it is mursal or mu‘dal (i.e., not sound). End quote from Nataa’ij al-Afkaar, 3/267
To sum up:
There is the hope that the one who recites this soorah will attain this great virtue and it will intercede for him before Allah and save him from the punishment of the grave. There are reports which speak in particular about giving extra attention to it at night or when going to sleep. So if a person strives to do that, it is a good thing, in sha Allah.
For more information, please see the answer to question no. 26240
And Allah knows best.