I visited Allah’s Apostle while he was suffering from a high fever. I touched him with my hand and said, “O Allah’s Apostle! You have a high fever.”
Allah’s Apostle said, “Yes, I have as much fever as two men of you have.”
I said, “Is it because you will get a double reward?”
Allah’s Apostle said, “Yes, no Muslim is afflicted with harm because of sickness or some other inconvenience, but that Allah will remove his sins for him as a tree sheds its leaves.”
Hadith – Bukhari 7:564