It was narrated from al-Harith bin Suwaid that 'Abdullah said:

I entered upon the Messenger of Allah (ﷺ) and he was running a fever. I touched him with my hand and said: O Messenger of Allah you are running a high fever. The Messenger Allah (ﷺ) said: “Yes, I am running a fever like two of you.” I said: Then you will have two rewards. The Messenger of Allah (ﷺ) said: “Yes. There is no Muslim who is afflicted with sickness or anything else, but Allah will erase thereby his bad deeds just as trees shed their leaves.”