Sahih Bukhari

Narrated Ibn Mas`ud:I visited the Prophet (ﷺ) while he was having a high fever. I touched him an said, ""You have a very high fever"" He said, ""Yes, as much fever as two me of you may have."" I said. ""you will have a double reward?"" He said, ""Yes No Muslim is afflicted with hurt caused by disease or some other inconvenience, but that Allah will remove his sins as a tree sheds its leaves