This is what Abu Huraira narrated to us from the Prophet and he transmitted some ahadith-one of them was that the Messenger of Allah (ﷺ) said: Let the heat become less severe before prayer, for the intensity of heat is from the exhalation of Hell.
Sahih Muslim Book 5, Hadith 233
← Previous Hadith This heat is from the exhalation of Hell-fire, so delay the prayer till it is cool.

Sahih Muslim Book 5, Hadith 232 Next Hadith → The Mu'adhdbin (the announcer of the hour of prayer) of the Messenger of Allah (ﷺ) called for the noon prayer. Upon this the Messenger of Allah (ﷺ) said: Let it cool down, let it cool down, or he said: Wait, wait for the intensity of heat is from the exhalation of Hell. When the heat is intense, delay the prayer till it becomes cooler. Abu Dharr said: (We waited) till we saw the shadow of the mounds.

Sahih Muslim Book 5, Hadith 234