Abdullah bin Mas’ud (r.a): I visited Allah’s Apostle (sallAllahu alayhi wasallam) 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 (sallAllahu alayhi wasallam) 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.”

(Bukhari)