Tafsir of Ghafir 40:1

Allah says,

حم

Ha Mim, We have already discussed the individual letters at the beginning of Surah Al-Baqarah, and there is no need to repeat the discussion here. In a Hadith recorded by Abu Dawud and At-Tirmidhi from one who heard it from the Messenger of Allah, it says:

إن بيتم الليلة فقولوا حم ﻻ ينصرون

When you go to bed tonight, recite Ha Mim, La Yunsarun.'' Its chain of narrators is Sahih. Allah says,

تنزيل الكتاب من الله العزيز العليم