﴿ وَأَمَّا ٱلَّذِينَ فِى قُلُوبِهِم مَّرَضٌۭ فَزَادَتْهُمْ رِجْسًا إِلَىٰ رِجْسِهِمْ وَمَاتُوا۟ وَهُمْ كَٰفِرُونَ ﴾

“But as for those in whose hearts is disease, each new message but adds another [element of] disbelief to the disbelief which they already harbour, and they die while [still] refusing to acknowledge the truth.”

(But as for those in whose hearts is disease) doubt and hypocrisy, (it only addeth wickedness to their wickedness) it only adds doubt to their doubt in what is revealed of the Qur'an, (and they die while they are disbelievers) inwardly in Muhammad (pbuh) and in the Qur'an.