Diseases are two types–Imaam Ibnul Qayyim
In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Diseases are of two types: The diseases of the heart and the diseases of the body. And both of them have been mentioned in the Qur’aan.
The diseases of the heart are two types:
 The disease of Shubhah (i.e. an affair of falsehood that is made to resemble truth) and the disease of Shak (i.e. doubt).
 The disease of Shahawaat (i.e. Lowly desires) and the disease of Ghay (i.e. straying from the right path). Both of them have been mentioned in the Qur’aan.
Allaah (The Most High) stated concerning the disease of Shubhah (i.e. an affair of falsehood that is made to resemble truth):
فِي قُلُوبِهِم مَّرَضٌ فَزَادَهُمُ اللَّهُ مَرَضًا
”In their hearts is a disease (of doubt and hypocrisy) and Allah has increased their disease.” [2:10]
Allaah (The Most High) said:
وَلِيَقُولَ الَّذِينَ فِي قُلُوبِهِم مَّرَضٌ وَالْكَافِرُونَ مَاذَا أَرَادَ اللَّهُ بِهَٰذَا مَثَلًا ۚ
”And that those in whose hearts is a disease (of hypocrisy) and the disbelievers may say: “What Allah intends by this (curious) example?” [74:31]
And Allaah (The Most High) stated about the one who is called to judge by the Qur’aan and the Sunnah, but he refuses and turns away:
وَإِذَا دُعُوا إِلَى اللَّهِ وَرَسُولِهِ لِيَحْكُمَ بَيْنَهُمْ إِذَا فَرِيقٌ مِّنْهُم مُّعْرِضُونَ
وَإِن يَكُن لَّهُمُ الْحَقُّ يَأْتُوا إِلَيْهِ مُذْعِنِينَ
أَفِي قُلُوبِهِم مَّرَضٌ أَمِ ارْتَابُوا أَمْ يَخَافُونَ أَن يَحِيفَ اللَّهُ عَلَيْهِمْ وَرَسُولُهُ ۚ بَلْ أُولَٰئِكَ هُمُ الظَّالِمُونَ
”And when they are called to Allah (i.e. His Words, the Qur’an) and His Messenger to judge between them, lo! a party of them refuse (to come) and turn away. But if the right is with them, they come to him willingly with submission. Is there a disease in their hearts? Or do they doubt or fear lest Allah and His Messenger () should wrong them in judgement. Nay, it is they themselves who are the Zalimun (polytheists, hypocrites and wrong-doers, etc.).[24:48-50]
This is the disease of Shubhah (i.e. an affair of falsehood that is made to resemble truth) and the disease of Shak (i.e. doubt).
As for the disease of lowly desires, Allaah (The Most High) said:
يَا نِسَاءَ النَّبِيِّ لَسْتُنَّ كَأَحَدٍ مِّنَ النِّسَاءِ ۚ إِنِ اتَّقَيْتُنَّ فَلَا تَخْضَعْنَ بِالْقَوْلِ فَيَطْمَعَ الَّذِي فِي قَلْبِهِ مَرَضٌ
”O wives of the Prophet! You are not like any other women. If you keep your duty (to Allah), then be not soft in speech, lest he in whose heart is a disease (of hypocrisy, or evil desire for adultery, etc.) should be moved with desire, but speak in an honourable manner.” [Ahzaab: Ayah:32]
This is the disease of the lowly desire for adultery, and Allaah knows best.
[Source: At-Tib An-Nabawiy of Imaam Ibnul Qayyim Al-Jawziyyah with notes of Al-Allaama Muhammad Haamid Al-Faqee: page: 3]