Musannaf Ibn Abi Shayba 3:909

Muhammad ibn Abd Allah al-Asadi narrated to us, he said: Bashir ibn Sulayman narrated to us, from al-Qasim ibn Safwan, from his father, he said: I heard the Prophet, peace and blessings of Allah be upon him, saying: "Delay the Dhuhr prayer until it cools down, for the intensity of the heat is from the scorching of Hell."