تبريد الحمى بالماء
Cooling the body with water during fever, based on the description of fever as a form of heat to be countered with cold.
الْحُمَّى مِنْ فَيْحِ جَهَنَّمَ فَأَبْرِدُوهَا بِالْمَاءِ
“Fever is from the heat of Hell, so cool it down with water.” (meaning, not a literal translation)
This hadith appears in multiple narrations with slightly varying context, some tied to a specific illness a companion experienced — across versions, the core instruction (cool the fever with water) remains consistent.
Ibn al-Qayyim explains this as cooling by cold water applied externally (poured or as a compress) rather than necessarily drinking large volumes, aimed at balancing the excess internal heat associated with fever. He discusses this within his broader hot/cold humoral framework, treating fever as an excess-heat state to be countered by its opposite quality — the same underlying logic seen in several other entries on this site.
Modern fever management for adults with routine viral fevers often doesn't require aggressive cooling — a lukewarm (not cold) sponge bath and adequate hydration are commonly recommended, while very cold water or ice can cause shivering that raises core temperature further. Medical guidance today is more nuanced about method and temperature than the classical instruction alone specifies.