Sahih Bukhari

Narrated `Abdullah bin Mas`ud:I visited Allah's Messenger (ﷺ) while he was suffering from a high fever. I touched him with my hand and said, ""O Allah's Messenger (ﷺ)! You have a high fever."" Allah's Messenger (ﷺ) 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 Messenger (ﷺ) 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