If one forgets some part of the quran after memorizig it and then repents, should one then revise the forgotten part for the repentance to be valid? If it has to be revised, then the surahs or rukoo's learned properly can be easily revised, but how can one revise verses learned from random locations when one does not remember those locations? Would this revision have to be done immediately or can one take his time in doing it (i.e. doing it in spare time)?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger.

We have underlined the prohibition of deliberately neglecting the revision of the memorized parts of the Quran and exposing oneself to forgetting it in fataawa 107125 and 256783, especially given that some scholars declared such an act a grave sin.

However, this applies to the person who deliberately neglects revising the Quran until he forgets it. On the other hand, he who keenly revises the Quran that he had memorized but forgets it due to his poor memorization or any other valid reason bears no sin for that; Allaah, The Exalted, does not burden the person beyond his capacity. Allaah, The Exalted, says (what means):

·    {...Allaah does not charge a soul except [according to] what He has given it...} [Quran 65:7]

·    {Allaah does not charge a soul except [with that within] its capacity...} [Quran 2:286]

Al-Khaadimi wrote:

“As for the report reading, 'The sins of my nation were shown to me, and I did not see any graver sin than a man forgetting a chapter or verse after having memorized it,' it refers to the case when one deliberately neglects the Quran that he had memorized and occupies himself with idle and unneeded activities, or (his forgetting it is) due to indifference or lack of respect to it or taking it lightly. This report is not in contradiction with the hadeeth that reads, ‘Allaah has forgiven for my followers mistakes and forgetfulness,’ because it refers to the sin of deliberately neglecting the memorized parts of the Quran by failing to revise it as due...” [Bareeqah Mahmoodiyyah]

The repentant is obliged to hasten to revise what he had memorized of the Quran and then forgot to the best of his ability, without delay, because repentance must not be delayed. Ar-Ramli was asked about the person who forgets the Quran after having memorized it and whether he is obliged to revise it or not, and if the answer was that he is obliged to revise it, is neglecting it then considered a grave sin or not, and does the religious ruling differ in case of an adult and a person under the age of puberty? He replied, “If the adult individual forgets the Quran out of neglect and laziness, it is considered a grave sin in this case, and he is obliged to memorize it if he can so as to escape this sin...” [Fataawa Ar-Ramli]

He is only obliged to do what is within his capacity and nothing beyond that; he should not exhaust himself or quit his job through which he earns his living and that he needs, the same as what scholars advised regarding making up for the missed prayers.

Allaah Knows best.