The Prophet ﷺ said: No man recites the Qur'an, then forgets it, but will meet Allah on the Day of Judgment in a maimed condition (or empty-handed, or with no excuse).  

قَالَ رَسُولُ اللَّهِ ﷺ مَا مِنِ امْرِئٍ يَقْرَأُ الْقُرْآنَ يَنْسَاهُ إِلاَّ لَقِيَ اللَّهَ ﷻ يَوْمَ الْقِيَامَةِ أَجْذَمَ