Nasr bin 'Imran bin Isam نصر بن عمران بن عصام · Chapters on Medicine

"For fever, and all pains, the Prophet (S.A.W) would teach them to say: Bismillahil-Kabir; a'udhu billahil-'Azimi min sharri kulli 'irqin na'arin, wa min sharri harrin-nar. (In the name of Allah the Great, I seek refuge with Allah the Magnificent from the evil of every gushing vein, and from the evil of the heat of the Fire)"