`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).
Sahih al-Bukhari Book 76, Hadith 38
← Previous Hadith When the helmet broke on the head of the Prophet (ﷺ) and his face became covered with blood and his incisor tooth broke (i.e. during the battle of Uhud), `Ali used to bring water in his shield while Fatima was washing the blood off his face. When Fatima saw that the bleeding increased because of the water, she took a mat (of palm leaves), burnt it, and stuck it (the burnt ashes) on the wound of Allah's Apostle, whereupon the bleeding stopped.

Sahih al-Bukhari Book 76, Hadith 37 Next Hadith → Whenever a lady suffering from fever was brought to Asma' bint Abu Bakr, she used to invoke Allah for her and then sprinkle some water on her body, at the chest and say, "Allah's Messenger (ﷺ) used to order us to abate fever with water."

Sahih al-Bukhari Book 76, Hadith 39