Sahih al-Bukhari 3263
Sahih al-Bukhari · Book 59: Beginning of Creation · The description of the (Hell) Fire and the fact that it has already been created
Narrated Aisha:
حَدَّثَنَا مَالِكُ بْنُ إِسْمَاعِيلَ ، حَدَّثَنَا زُهَيْرٌ ، حَدَّثَنَا هِشَامٌ ، عَنْ عُرْوَةَ ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " الْحُمَّى مِنْ فَيْحِ جَهَنَّمَ، فَأَبْرِدُوهَا بِالْمَاءِ " .
The Prophet (ﷺ) said, "Fever is from the heat of the (Hell) Fire, so cool it with water."