Shaitaan sticks to the heart of the child of Adam. When he does Zikr of Allah, he (Shaitaan) runs away from him. And when the child of Adam becomes careless from the Zikr of Allah, the Shaitan begins to put was-wasah (evil suggestion​s) into his heart.” [Bukhari]

There is a polish for everything that takes away rust; and the polish for the heart is the remembrance of Allah.” (Bukhari)