Uthman bin 'Asim bin Husayn عثمان بن عاصم بن حصين أبو حصين · Chapters on Medicine

"When one of you suffers from fever - and indeed fever is a piece of the Fire - let him extinguish it with water. Let him stand in a flowing river facing the direction of it and say: Allahummashfi 'abdaka wa saddik Rasulak ('In the name off Allah. O Allah! Cure your slave and testify to Your Messenger.)' Doing so after Salat As-Subh(Fajr) and before the rising of the sun. Let him submerse himself in it three times, for three…