Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) said: "The rewards and good deeds of my Ummah were presented before me, even to the extent of the straw that a person removes from the mosque. And the sins of my Ummah were also presented before me, and I did not see any sin greater than that of a person to whom a Surah or verse of the Qur'an was given (he memorized it), then he forgot it (neither remembered it nor acted upon it)."