From Sahih Bukhari (Hadith 5723):
Narrated Nazi':`Abdullah bin `Umar said, "The Prophet (ﷺ) said, 'Fever is from the heat of Hell, so put it out (cool it) with water.' " Nafi` added: `Abdullah used to say, "O Allah! Relieve us from the punishment," (when he suffered from fever)
Reference: Bukhari 5723