What is the ruling on one who forgets the Qur'an after memorizing it

Question : The questioner on the line with us says: Honorable Shaykh, what is the ruling on memorizing the verses of the Qur'an and then forgetting them?

Answer : Memorizing the Qur'an by heart is a great blessing. A person should, indeed, it is obligatory for him, to give thanks to Allah, Lord of the worlds, for He has bestowed this blessing upon him, which He has withheld from many people. And since it is a blessing from Allah the Exalted, a person should not waste it. The Prophet (peace and blessings be upon him) urged us to keep the Qur'an fresh, and we ask Allah for help.
He said that the Qur'an is more likely to slip away from the mind than a camel from its tether. Therefore, a person must review what he has memorized, and he knows his own nature best. If he is quick to forget, he should review it frequently; if he is slow to forget, he should review it as much as is sufficient for him. A warning has been reported regarding one who memorizes a verse from the Book of Allah and then forgets it, but if the forgetting is not intentional, nor due to negligence or lack of attention to the Noble Qur'an, then there is no sin on the person for it. Yes.