The Mu'adh-dhin (call-maker) of the Prophet (ﷺ) pronounced the Adhan (call) for the Zuhr prayer but the Prophet said, "Let it be cooler, let it be cooler." Or said, 'Wait, wait, because the severity of heat is from the raging of the Hell-fire. In severe hot weather, pray when it becomes (a bit) cooler and the shadows of hillocks appear."
Sahih al-Bukhari Book 9, Hadith 13
← Previous Hadith Allah's Messenger (ﷺ) said, "If it is very hot, then pray the Zuhr prayer when it becomes (a bit) cooler, as the severity of the heat is from the raging of the Hell-fire."

Sahih al-Bukhari Book 9, Hadith 12 Next Hadith → The Prophet (ﷺ) said, "In very hot weather delay the Zuhr prayer till it becomes (a bit) cooler because the severity of heat is from the raging of the Hell-fire. The Hell-fire of Hell complained to its Lord saying: O Lord! My parts are eating (destroying) one another. So Allah allowed it to take two breaths, one in the winter and the other in the summer. The breath in the summer is at the time when you feel the severest heat and the breath in the winter is at the time when you feel the severest cold."

Sahih al-Bukhari Book 9, Hadith 14