Mishkat al-Masabih 23 Medicine and Spells كتاب الطب والرقى 12

وَعَنْ عَائِشَةَ وَرَافِعِ بْنِ خَدِيجٍ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «الْحمى من فيج جَهَنَّم فَأَبْرِدُوهَا بِالْمَاءِ»

‘A’isha and Raf’i b. Khadij reported the Prophet as saying: “Fever is due to the vehemence of the heat of hell, so cool it with water.” (Bukhari and Muslim.).