Learning the Qur'an by Heart

To memorise the entire Qur'an and become a ḥāfiẓ is farḍ kifāyah: a communal obligation, so that within a given locality or region at least a group of Muslims must undertake it, or the whole locality bears responsibility for the neglect on the Day of Judgement. Some of the scholars regard the pursuit of this particular achievement as sunnat al-ʿayn, so strongly does it follow the practice of the Messenger of Allah (peace be upon him), who committed the Book of Allah to memory to the fullest extent possible. To sit and commit even a page, a short sūrah or a portion of a long one to memory is more meritorious, more virtuous, and earns more reward than standing and praying voluntary prayer — not the farḍ prayer, but nawāfil, voluntary ṣalāh — and opening the Qur'an to memorise even a single line or two surpasses standing in voluntary prayer in reward.

To recite the Qur'an outside of ṣalāh, tilāwah, is itself the greatest form of worship available outside the prayer, as the Messenger of Allah (peace be upon him) states: the best worship of his Ummah is the recitation of the Qur'an. In a different hadith he states that the best among the believers are those who learn the Qur'an and teach it to others — the very best there is.