From Sahih Muslim (Hadith 5760):
Rafi' b. Khadij reported:I heard Allah's Messenger (ﷺ) as saying: The fever is due to the intense heat of Hell, so cool it down in your (bodies) with water. Aba Bakr has made no mention of the word" from you" ('ankum), but he said that Rafi' b. Khadij had informed him of it
Reference: Muslim 5760