The ruling on one who forgets the Qur'an due to negligence

Question:
Honorable Shaykh, what is the ruling on one who memorizes the Noble Qur'an for the sake of study, then forgets it due to his negligence and indifference? Does he commit a sin? Is it obligatory for him to memorize it again?

Answer:
In any case, the Messenger (peace and blessings be upon him) commanded the review of the Qur'an and the preservation of its memorization and recitation. He informed us that it slips away just as camels slip away from their tethers if a person does not preserve it. So, for a person to memorize the Qur'an or part of the Qur'an and then forget it is undoubtedly a loss; it is a loss. And if he forgot it due to negligence and indifference, he may commit a sin in this, because this is abandoning the Qur'an. Abandoning the Qur'an has types: abandoning the Qur'an by not believing in it, or abandoning the Qur'an by not reciting it, or by reducing its recitation—this is abandonment. Or abandoning the Qur'an by not understanding its meanings—this is also abandonment. Or abandoning the Qur'an by not learning it and turning to it. All of this is among the types of abandonment. So, if the loss of the Qur'an is due to an illness or a condition that afflicted a person and weakened his memory, there is no blame on him because it is known. But if the forgetting of the Qur'an is due to negligence, then this is abandonment, and it is not permissible for a person to abandon the Qur'an. So he should think about reciting the Qur'an and...