Do not blaspheme fever, because it wipes out the sins of the children of Adam

The Messenger (peace be upon him) entered upon Umm As-Saaib and said to her: "What is the matter with you, O Umm Saaib that you are trembling'" She said "Fever, (there is) no blessing of Allah in it". He (peace be upon him) said "Do not blaspheme fever, because it wipes out the sins of the children of Adam, as the bellows extract the dirt from iron ".[Muslim]