I have memorized the Qur’ān and I have forgotten a lot due to my over interest in understanding and comprehending the Qur’ān. In other words, I read translations and exegeses of the Qur’ān a lot so that I am able to understand it properly but I don’t pay the required attention to memorize it again. So is it a great sin?
This often happens with people whose native language is not Arabic and who are made to memorize the Qur’ān by rote without being taught Arabic. Forgetting the Qur’ān in this manner cannot be classified a sin.
However, you should devote some time for recalling what you have forgotten. You will need less time to refresh your memory. And since you are now well-versed with its meanings also, you will greatly enjoy reciting it out by heart whether in the prayer or while traveling etc.
Memorizing the Qur’ān is also one way of preserving the Qur’ān and transferring it to the next generation. So when you memorize the Qur’ān, you actually contribute in the divine scheme of protection of Qur’ān. Hence if you are able to do so, it will reap great reward for you as well.
Also, it is expected from a Qur’ān memorizer to be a person who does not merely recite and understand the Qur’ān. He should be a person who follows the teachings of the Qur’ān also. The Qur’ān, you would agree is not merely an intellectual reading. It is a Book that is meant to change one’s life and outlook.