Soorah Al-Mulk is the 67th Chapter in the Qur'aan and begins with the Verse:
Blessed is He in whose hand is dominion, and He is over all things competent –
تَبَارَكَ الَّذِي بِيَدِهِ الْمُلْكُ وَهُوَ عَلَىٰ كُلِّ شَيْءٍ قَدِيرٌ
Benefits of Soorah Al-Mulk
Narrated Abu Hurairah: that the Prophet (sallallaahu alayhi wa sallam) said:
"Indeed there is a Soorah in the Qur'aan of thirty Ayat, which intercedes for a man until he is forgiven. It is [Soorah] Tabarak Alladhi Biyadihil-Mulk."
[Jaami Al-Tirmidhi Hadith No. 2891]
ففي الحديث أنه صلى الله عليه وسلم قال: سورة تبارك هي المانعة من عذاب القبر. رواه الحاكم، وقال: صحيح الإسناد ـ ووافقه الذهبي
The Messenger of Allaah (sallallaahu alayhi wa sallam) said:
Soorah Tabaaraka is Al-Maani'ah [that which prevents] from the torment of the grave.
Al-Haakim said that this Hadith has a chain of narrators which is Sahih [authentic]. Al-Dhahabi agreed with him.
Why is Soorah Al-Mulk called Al-Maani'ah?
Al-Maani'ah means that which prevents. The scholars have explained that the reason why the Soorah is called Al-Maani'ah is because it prevents from the torment of the grave or prevents from disobedience which is the cause for being tormented in the grave.
قال المباركفوري في تحفة الأحوذي: المانعة ـ أي تمنع من عذاب القبر، أو من المعاصي التي توجب عذاب القبر
Imaam Al-Suyooti said:
فعرف من مجموعها أنها تجادل عنه في القبر وفي القيامة لتدفع عنه العذاب وتدخله الجنة
It has come to be known that the Soorah will debate on behalf of him [the one who recited it regularly when alive] in the grave and on the Day of Judgment to ward off from him the torment and enter him into Paradise.