Just before concluding the prayer, as one last request before exiting from our meeting with our Lord, we are taught to ask Allah for refuge in four things as we say, اللهم إني أعوذ بك من عذاب جهنم ومن عذاب القبر , commonly translated to, “O Allah, I take refuge in You from the punishment of the Hellfire and from the punishment of the grave.”
The word عذاب comes from the meaning of abstention and prevention. And when used based on this meaning in the Qur’an, the term عذاب is used in the Qur’an to connote punishment, castigation, or chastisement, because **punishments restrain and prevent offenders from repeating the offence, and prevent others from doing the like of that which the offender has done.
The word جهنم comes from a word that refers to a well that is so deep that whoever falls into it will perish. And thus the Hellfire was referred to as جهنم due to the depth of its pit. Seeking refuge in Allah from the Hellfire's punishment inherently means seeking His protection against engaging in any misdeeds that could result in such punishment, as well as seeking shelter from the repercussions of any misdeeds already committed.
And the word قبر is rooted in the concept of burying or hiding something within the earth, thus it is associated with a grave. Seeking refuge in Allah from the punishment of the grave essentially means seeking His protection from any form of punishment that might occur in the period between our death and resurrection. This is because the actual fate of our bodies is uncertain; they might not necessarily be buried but could, for instance, be consumed by wild animals or be burned to ashes.
So when we say, اللهم إني أعوذ بك من عذاب جهنم ومن عذاب القبر we are essentially saying, “O Allah, I take refuge in You and seek Your protection from committing any action that will lead us to be subjected to the punishment of a Hellfire that is so deep that it will cause whoever falls into it to perish, and ask You to forgive me of any such actions already committed. Likewise, I take refuge in You from any punishment that may befall me between my death and my resurrection.”