Zunubai suna haifar da wasu zunuban, har sai mutum ya same shi da wahalar barin su. Wani malami na da can ya ce: "Daga cikin azabar zunubi akwai aikata wani zunubin bayansa. Kuma daga cikin sakamakon aikin alheri akwai yin wani aikin alherin bayansa. Idan mutum ya yi aikin alheri, wani aikin alheri daban zai ce masa: 'Ka yi ni ma.' Idan ya yi shi, na uku zai ce haka, haka kuma har zuwa karshe; saboda haka, ayyukan alherinsa da ladan su suna karuwa. Abu daya ke faruwa, (amma ta hanya mara kyau), idan mutum ya aikata zunubi." Saboda haka, ayyuka nagari da marasa kyau suna tabbata a matsayin dabi'u da halaye a rayuwar mutum. Idan mai adalci ya rasa wani aikin biyayya, zai ji matsi. Zai ji kamar kifi da ya fita daga ruwa, kuma ba zai samu natsuwa ba sai ya cika wajibanshi. A daya bangaren, idan mai zunubi ya rasa aikata zunubi, zai ji matsi, kuma ba zai samu sauki ba sai ya aikata wannan zunubin. Hakika, da yawa daga masu zunubi suna aikata zunubansu ba tare da jin dadinsu ba, kawai don su guje wa alamomin janyewa idan sun rasa su. Wani sanannen mai zunubi ya taba cewa: "Gilashin giya daya na sha don jin dadi, sai na biyo shi da wani don in warkar da kaina daga (shan) na farko."

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)."

Zunubai suna raunana ƙudurin zuciya, kuma suna ƙarfafa niyyar aikata ƙarin zunubai. Sannan ƙudurin tuba yana raguwa a hankali, har sai ya ɓace gaba ɗaya daga zuciya. Da zarar rabin zuciyar mutum ta mutu, ba zai ƙara iya tuba zuwa ga Allah ba. Saboda haka, zai bayyana tuba da ƙarfi, alhali zuciyarsa har yanzu tana manne da waɗannan zunubai, yana dagewa a kan aikata su ta kowace hanya mai yiwuwa. Don haka wannan yana ɗaya daga cikin cututtuka mafi tsanani na zuciya, kuma mafi lalatarwa cikin dukkansu.

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.