"The Messenger of Allah said: 'Wait for it to cool down before you pray the Zuhr.'"
Sunan Ibn Majah Book 2, Hadith 15
← Previous Hadith We were praying Zuhr with the Messenger of Allah at the time of intense heat (i.e., midday when the sun has just passed its zenith) and he said to us, "Wait for it to cool down before you pray, for intense heat is from the flaring up of the Hell-fire."

Sunan Ibn Majah Book 2, Hadith 14 Next Hadith → The Messenger of Allah used to pray 'Asr when the sun was still hot and high, and if a person were to go to the suburbs (of Al-Madinah) he would be able to reach it while the sun was still hot and high.

Sunan Ibn Majah Book 2, Hadith 16