It is narrated from Sayyiduna Khabbab (may Allah be pleased with him) that he said: We complained to the Messenger of Allah (peace and blessings be upon him) about the intensity of the heat, but he (peace and blessings be upon him) did not accept our complaint. I asked Abu Ishaq: About Zuhr? He said: Yes. I said: About praying it early? He said: Yes, about praying Zuhr early.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2065
It is narrated from Sayyiduna Khabbab bin al-Aratt (may Allah be pleased with him) that he said: We made a request to the Messenger of Allah (peace and blessings be upon him) about the intensity of the heat, but he (peace and blessings be upon him) did not accept our complaint and said: "When the sun has declined, then pray."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2066
It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) that he said: I used to pray Zuhr with the Messenger of Allah (peace and blessings be upon him). I would take a handful of pebbles in my hand so that they would cool down, and I would place them at the spot of my prostration so that I could prostrate on them (avoiding the heat of the ground); (this was because of the intensity of the heat).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2067