“There is no doubt that the heart becomes covered with rust, just as metal dishes—silver, and their like—become rusty. So the rust of the heart is polished with dhikr (remembrance of Allaah), for dhikr polishes the heart until it becomes like a shiny mirror. However, when dhikr is abandoned, the rust returns; and when it commences then the heart again begins to be cleansed. Thus the heart becoming rusty is due to two matters: sins and ahafah (neglecting remembrance of Allaah ). Likewise, it is cleansed and polished by two things : istighfaar (seeking Allaah’s forgiveness) and dhikr.