Is it permissible to suffice with memorizing half of the Qur’an in order to preserve it and avoid forgetting it, and is there any sin upon the one who does so?

Memorizing and reciting the Quran are among the greatest acts of worship, and its reciter achieves a magnificent reward; for each letter yields ten good deeds. Memorizing the entire Quran is not an individual obligation (fard ayn) upon every Muslim, but rather it is a communal obligation (fard kifayah) such that if some individuals undertake it, the obligation falls away from the rest. Therefore, there is no sin upon the questioner for only memorizing half of the Quran. However, it is recommended to strive to memorize the entire Quran and to regularly recite and review it, due to the abundant goodness and reward contained therein.