If the first inward thought is not warded off, it will generate a desire, then the desire will generate a wish, and the wish will generate an intention, and the intention will generate the action, and the action will result in ruin and divine wrath. So evil must be cut off at its root, which is when it is simply a thought that crosses the mind, from which all the other things follow on.
Al-GhazaliDeclare your jihad on thirteen enemies you cannot see - Egoism, Arrogance, Conceit, Selfishness, Greed, Lust, Intolerance, Anger, Lying, Cheating, Gossiping and Slandering. If you can master and destroy them, then will be ready to fight the enemy you can see.
Al-GhazaliYou must convince your heart that whatever Allah has decreed is most appropriate and most beneficial for you.
Al-GhazaliDo not dispute with anyone in any matter as far as possible. For in argumentation lies much harm and its evil is greater than its benefit.
Al-GhazaliWhen you have a bad suspicion about a Muslim in your heart, you should increase your consideration toward him and make dua for him. This way you will infuriate Satan and will be able to drive him away. Because of this, Satan will be reluctant to put evil thoughts into your heart, afraid that you would increase your consideration towards your brother and will make dua for him again.
Al-Ghazali