Praise be to Allah.
Whoever memorizes Qur’aan and acts upon it, Allaah will reward him and honour him greatly for that, so that he will rise in status in Paradise to a level commensurate with what he memorized of the Book of Allaah.
Al-Tirmidhi (2914) and Abu Dawood (1464) narrated from ‘Abd-Allaah ibn ‘Amr that the Prophet (peace and blessings of Allaah be upon him) said: “It will be said to the companion of the Qur’aan: Recite and rise in status, recite as you used to recite in the world, for your status will be at the last verse that you recite.” This hadeeth was classed as saheeh by al-Albaani in al-Silsilah al-Saheehah, 5/218, no. 2240, after which he said:
Note that what is meant by the “companion of the Qur’aan” is the one who memorizes it by heart, as the Prophet (peace and blessings of Allaah be upon him) said, “The one who knows more Qur’aan should lead the people in prayer,” meaning the one who has memorized the most. The differentiation in status in Paradise will depend on how much was memorized in this world, not how much one will recite on that day as some people imagine. This clearly points to the virtue of the hafiz who has memorized the Qur’aan, but that is subject to the condition that he memorizes it for the sake of Allaah, not for worldly purposes or financial gain. Otherwise the Prophet (peace and blessings of Allaah be upon him) said: “Most of the hypocrites of my ummah are among those who have memorized Qur’aan.”
Concerning the virtue of the hafiz who memorizes the Qur’aan, al-Bukhaari (4937) narrated from ‘Aa’ishah that the Prophet (peace and blessings of Allaah be upon him) said: “The likeness of the one who reads Qur’aan and memorizes it is that he is with the righteous honourable scribes. The likeness of the one who reads it and tries hard to memorize it even though it is difficult for him, he will have two rewards.”
For the hafiz who has memorized the Qur’aan, praying qiyaam al-layl is easy. And the Qur’aan will intercede for him on the Day of Resurrection, because the Prophet (peace and blessings of Allaah be upon him) said: “Fasting and the Qur’aan will intercede for a person on the Day of Resurrection. Fasting will say, ‘O Lord, I deprived him of food and desires during the day, so let me intercede for him.’ The Qur’aan will say, ‘O Lord I deprived him of his sleep at night, so let me intercede for him.’ Then they will both intercede for him.” Narrated by Ahmad, al-Tabaraani and al-Haakim; classed as saheeh by al-Albaani in Saheeh al-Jaami’, no. 3882
And Allaah knows best.
It should be noted here that there is a weak (da’eef) hadeeth that is quoted concerning the virtue of memorizing Qur’aan. This hadeeth says, “The bearer of the Qur’aan, if he regards what it permits as halaal and what it forbids as haraam, he will intercede for ten of his family members on the Day of Resurrection, all of whom deserved to enter Hell.” This was narrated by al-Bayhaqi in Shu’ab al-Eemaan (The Branches of Faith) from Jaabir; it was classed as da’eef by al-Albaani in Da’eef al-Jaami’.