The ones in whose hearts is a disease) meaning: doubt. (So it added filth to their filth) that is: their rejection of it added disbelief to their disbelief. (And they die while they are disbelievers) He says: they die in a state of disbelief.
Surah at-Tawbah from verse (126) to verse (127).
الَّذِينَ فِي قُلُوبِهِمْ مَرَضٌ) ﴿شَكٌّ﴾ (فزادتهم رجساً إِلَى رجسهم﴾ أَيْ: زَادَهُمْ تَكْذِيبُهُمْ بِهَا كُفْرًا إِلَى كُفْرِهِمْ (وَمَاتُوا وَهُمْ كَافِرُونَ يَقُولُ: إِنَّهُمْ يَمُوتُونَ عَلَى الْكُفْرِ.
سُورَة التَّوْبَة من الْآيَة (١٢٦) إِلَى الْآيَة (١٢٧).
