Sahih al-Bukhari 3259
Sahih al-Bukhari · Book 59: Beginning of Creation · The description of the (Hell) Fire and the fact that it has already been created
Narrated Abu Sa`d:
حَدَّثَنَا مُحَمَّدُ بْنُ يُوسُفَ ، حَدَّثَنَا سُفْيَانُ ، عَنِ الأَعْمَشِ ، عَنْ ذَكْوَانَ ، عَنْ أَبِي سَعِيدٍ ، رضى الله عنه قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم " أَبْرِدُوا بِالصَّلاَةِ فَإِنَّ شِدَّةَ الْحَرِّ مِنْ فَيْحِ جَهَنَّمَ " .
The Prophet (ﷺ) said, "Delay the (Zuhr) Prayer till it gets cooler, for the severity of heat is from the increase in the heat of Hell (fire).