From "The Illness and the Cure" by Ibn Qayyim.
Published by Germantown Masjid 2007.
Translated by Abu Alim Rasheed Salahuddin and Abu Aaliyah Abdullah bin Dwight Battle
From among the punishments of sin is that disobedience becomes a fierce enemy to mankind like an army which fortifies itself and prepares for war.
That is to say that Allaah tests the Son of Adam with an enemy who does not leave his side for a single moment; a companion who is never remiss in thinking about him, nor is he neglectful of him. This adversary to man, Iblees and his tribe, are able see the human being from a standpoint where he can’t see them. He exerts every effort to unleash his hostility under every circumstance.
In his plotting, he doesn’t leave anything out. Iblees is able to reach his foe and attach himself to him. This opponent seeks the help of the Shayateen and Jinn in his battle against the offspring of Adam. He throws his net over them and wishes disaster. This enemy lays traps around the servant. He lays these traps and nets for him and says to his helpers," Draw near to your enemy, and the enemy of your father! Don't let him slip away from you and attain his portion in the Paradise, leaving you to attain your share of the fire; his portion is mercy and your portion shall be a curse. You are aware of the disgrace, curse and the separation from Allaah's mercy that has been inflicted upon me. Adam is the cause of that. So, exert every effort to sway his progeny to join us as companions in this misery. And remember a band of them have already escaped us whose righteous are in Jannah.
Allaah has informed us about our enemy. He has commanded us to stand ready against him when He told Adam that his descendants would be tested with an enemy accompanied by armies and forces that would be given authority over them. Also, in their encounter with this foe, they should be aware that the army of their enemy is reinforced by soldiers and comrades. Know that the battle is waged in this abode during the extent of his life which is, in comparison to the next life, is like the extent of one breath.
Allaah has purchased from the believers as the cost for entering Jannah, their souls and wealth. They fight for the sake of Allaah. They kill and are killed-all for the pleasure of their Lord. Allaah has informed us of this sure promise in the most honorable of books- The Torah, The Injeel and the Quran .He states that He doesn't break any promise. Following this, Allaah orders the servants to rejoice in this bargain. Whosoever wants to know the value of this trade then let him look to who is the purchaser? Let him look at the cost that is paid for this commodity. And look to He who fulfills this contract. Is there any success greater than this? Is there a transaction more profitable than this? Allaah has guaranteed this for the believers in....