Hazrat Anas (Radiyallahu Anhu) reports that Rasulullah (Sallallahu Alayhi Wasallam) said: “The good deeds of my ummah were presented to me including the (reward of) removing some small dirt from the musjid. The sins of my ummah were (also) presented to me. I did not find any sin worse than (the sin of) that person who was granted (the knowledge of) a surah or a verse of the Qur’an and then he forgot it”. (Abu Dawood)