Abu Dharr said:We were in the company of the Prophet (ﷺ). The mu'adhdhin intended to call for the Zuhr prayer. He said: Make it cooler. He then intended to call for prayer. He said twice or thrice: Make it cooler. We then witnessed the shadow of the mounds. He then said: The intensity of heat comes from the bubbling over of the Hell ; so when the heat is violent, offer (the Zuhr) prayer when it becomes cooler

English translation · Sunan Abu Dawud