Spiritual Disease and Its Cure by Imam Shams-ud-Deen Muhammad bin Abi Bakr bin Qayyim AlJ awziyyah

Sins lead to the production of other sins, until one finds it hard to give them up. A scholar of the past has said: "Among the punishments for a sin is committing a subsequent sin . And among the recompenses for a good deed is doing a subsequent good deed. When a person does a good deed, another good deed besides it says: 'Do me as well.' If he does it, a third one says likewise, and so on; therefore, his good deeds, and recompense for them, increase. The same thing occurs, (but in a negative way), when a person commits a sin." Consequently, good and bad deeds become established as habits and attributes in one's life. If a righteous person misses an obedient act, he/she would feel strained. He/she would feel like a fish out of water, and would remain calm only once he/she fulfilled his/her obligations. On the other hand, if a sinner misses a sin, he/she would feel strained, and would be only relax once he/she had committed that sin. In fact, many sinners commit their sins without savouring them, just to prevent the withdrawal symptoms of missing them. One such prominent sinner has said: "One glass (of wine) I drank for pleasure, followed by another to heal myself from it (the first drink)."

Sins weaken the determination of the heart, and strengthen the willpower to commit more sins. The resolve for repentance is then weakened gradually, until it is totally removed from the heart. Once half of one's heart is dead, one could no longer repent to Allah ~- So, he/she would express repentance intensely, while his heart is still attached to these sins, insisting on committing them in any possible manner. So this is one of the most serious ailments of the heart, and the most destructive of all.