Sickness washes away the dirt of sins like soap, and cleanses. It is established in an authenticated hadith that illnesses are expiation for sins. It says, "As ripe fruits fall from the tree when it is shaken, so the sins of a believer fall away with the shaking during illness".
Bediuzzaman Said Nursi was a 20th-century Turkish scholar of Islam and philosophy who advocated compatibility of Islamic thought with modernity. He was the author of the Risale-i Nur, a 5,000-page modern commentary on the Qur'an.