فِى قُلُوبِهِم مَّرَضٌ فَزَادَهُمُ اللَّهُ مَرَضًا وَلَهُمْ عَذَابٌ أَلِيمٌ بِمَا كَانُواْ يَكْذِبُونَ
“In their hearts is disease, so Allah has increased their disease; and for them is a painful punishment because they [habitually] used to lie.”
The disease in their hearts is the disease of ‘doubt. Allah subhanahu wa ta’ala has increased them in their doubts.
Abdur-Rahman bin Zayd bin Aslam commented on it as,
“A disease in the religion, not a physical disease. They are the hypocrites and the disease is the doubt that they brought to Islam. ‘And Allah has increased their disease’ means, increased them in their shameful behavior.”
Here, Allah subhanahu wa ta’ala tells us another trait of the hypocrites (munafiqeen) that their hearts are full of desires, worldly plans, and doubts about Deen. Their disease of lust has been increased because they did not worry about it or sought treatment for it.
Why did their disease become incurable?
The answer is their doubt in Qur’an and Prophethood. The insincere man who thinks he can get the best of both worlds by compromising with good and evil only increases the disease of his heart, because he is not true to himself.
Even the good that comes to him, he can pervert to evil. So the rain, which fills out the ear of corn or lends fragrance to the rose also lends strength to the thorn or adds strength to the poison of the deadly nightshade. Another trait is their lie, they are habitual to lie themselves and to others. If anyone like to avoid punishment should leave lie. They are told you will have grievous penalty because you are in habit of lying and you are also untrue to yourself.
Aleem Azab is big punishment; never exaggerate things just for fun or to increase your importance in eyes of others. It is false and disliked by Allah.
وَإِذَا قِيلَ لَهُمْ لاَ تُفْسِدُواْ فِى الأَرْضِ قَالُواْ إِنَّمَا نَحْنُ مُصْلِحُونَ
“And when it is said to them, ‘Make not mischeif on earth,’ they say, ‘We are but reformers.'”
It is indicated towards these non-believers and hypocrites (munafiqeen), who have lost their vision to see the truth. Allah is warning them not to cause corruption on earth, leave your evil actions. They actually do not know the difference between right and wrong. They think they are peacemaker but in actual they are in ignorance and encouraging evil.
“And when it is said to them: ‘Do not make mischief on the earth,’” means, do not commit acts of disobedience on the earth. Their mischief is disobeying Allah, because whoever disobeys Allah on the earth, or commands that Allah be disobeyed, he has committed mischief on the earth. Peace on both the earth and in the heavens is ensured (and earned) through obedience (to Allah). Ar-Rabi` bin Anas and Qatadah said similarly. This Ayah means that the hypocrites’ behavior, and their claim that it is for peace, is itself mischief, although in their ignorance, they do not see it to be mischief.
Since the outward appearance of the hypocrite displays belief, he confuses the true believers. Hence, the deceitful behavior of the hypocrites is an act of mischief, because they deceive the believers by claiming what they do not believe in, and because they give support and loyalty to the disbelievers against the believers.
If the hypocrite remains a disbeliever (rather than pretending to be Muslim), the evil that results from him would be less. Even better, if the hypocrite becomes sincere with Allah and makes the statements that he utters conform to his deeds, he will gain success.
The hypocrites have two characteristics, they lie and they deny the Unseen.
Do not take disbelievers as protectors or helpers or friends instead of believers.