1: The prevention of knowledge: Knowledge is a light which Allaah throws into the heart and disobedience extinguishes this light. Imaam Shaafi’ee (rahimahullah) said: “I complained to Wakee’ about the weakness of my memory, so he ordered me to abandon disobedience. And informed me that the knowledge is light. And that the light of Allaah is not given to the disobedient. “
2: The prevention of sustenance: Just as Taqwaa brings about sustenance, the abandonment of Taqwaa causes poverty. There is nothing which can bring about sustenance like the abandonment of disobedience.
3: The prevention of obedience (to Allaah): If there was no other punishment for sin other than that it prevents one from obedience to Allaah then this would be sufficient.
4: Disobedience weakens the heart and the body: Its weakening the heart is something which is clear. Disobedience does not stop weakening it until the life of the heart ceases completely.
5: Disobedience reduces the lifespan and destroys any blessings: Just as righteousness increases the lifespan, sinning reduces it.
6: Sins weaken the hearts will and resolve: The desire for disobedience becomes strong and the desire to repent becomes weak bit by bit until the desire to repent is removed from the heart completely.
7: Every type of disobedience is a legacy of a nation from among the nations which Allaah destroyed. Sodomy is a legacy of the People of Lot, taking more than one’s due right and giving what is less is a legacy of the People of Shu’ayb, seeking greatness in the land and causing corruption is a legacy of the People of Pharoah and pride/arrogance and tyranny is a legacy of the People of Hud. So the disobedient one is wearing the gown of some of these nations who were the enemies of Allaah.
8: Disobedience is a cause of the servant being held in contempt by his Sustainer. Al-Hasan al-Basree (rahimahullah) said: They became contemptible in (His sight) so they disobeyed Him. If they were honorable (in His sight) He would have protected them. Allah the Exalted said: “And whomsoever Allaah lowers (humiliates) there is none to give honor.”
9: The servant continues to commit sins until they become very easy for him and seem insignificant in his heart and this is a sign of destruction. Every time a sin becomes insignificant in the sight of the servant it becomes great in the sight of Allaah. Ibn Mas’ood (radiy Allahu anhu) said: Indeed, the believer sees his sins as if he was standing at the foot of a mountain fearing that it will fall upon him and the sinner sees his sins like a fly which passes by his nose so he tries to remove it by waving his hand around. [Bukhaari]
10: Disobedience inherits humiliation and lowliness. Honor lies in the obedience of Allaah. Abdullaah ibn al-Mubaarak said: “I have seen sins kill the hearts. And humiliation is inherited by their continuity. The abandonment of sins gives life to the hearts. And the prevention of your soul is better for it.”
11: Disobedience corrupts the intellect. The intellect has light and disobedience extinguishes this light. When the light of the intellect is extinguished it becomes weak and deficient.
12: When disobedience increases, the servant’s heart becomes sealed so that he becomes of those who are heedless. The Exalted said: “But no! A stain has been left on their hearts on account of what they used to earn (i.e. their actions).”
13: Sins cause the various types of corruption to occur in the land. Corruption of the waters, the air, the plants, the fruits and the dwelling places. The Exalted said: “Mischief has appeared on the land and the sea on account of what the hands of men have earned; that He may give them a taste of some of (the actions) they have done, in order that they may return (to Him).”
14: Sins are the cause of Allaah forgetting His servant, abandoning him and leaving him to fend for himself with his soul and shaytaan and in this is the destruction from which no deliverance can be hoped for.
15: Sins remove the servant from the realm of Ihsaan (doing good) and he is prevented from (obtaining) the reward of those who do good. When Ihsaan fills the heart it prevents it from disobedience.
16: Disobedience causes the favors (of Allaah) to cease and make His revenge lawful. No blessing ceases to reach a servant except due to a sin and no retribution is made lawful upon him except due to a sin. Ali (radiy Allahu ‘anhu) said: No trial has descended except due to a sin and it (the trial) is not repelled except by repentance. Allaah the Exalted said: “Whatever misfortune afflicts you then it is due to what your hands have earned and (yet) He pardons many.” And the Exalted also said: “That is because never will Allaah change the favor He has bestowed on a people until they change what is with themselves.”
Imaam Ibn Qayyim Al-Jawziyyah
Source: From his Book Al-Jawaab al-Kaafee