Shaytan’s Three Angles of Attack – Ibn Qayyim Al-Jawzīyah, Al-Fawaa`id
Every intelligent person knows that Shaytān has no way to [attack] him except from three angles:
1. Extravagance. [A person] takes more than he needs, so it becomes superfluous; and [surplus] is the share of Shaytān and his point of entry to the heart. The way to avoid this is to avoid giving the self all it wants of food, sleep, pleasure and comfort. When you close this door, you will be safe from the enemy entering through it.
2. Heedlessness. One who remembers [Allāh] is in an impenetrable fortress. If he becomes forgetful and heedless, he opens the gates of the fortress, and the enemy enters, after which it is difficult to expel him.