In severe heat, offer Zuhr prayers when it becomes (a bit) cooler

Narrated Abu Dhar Al-Ghifar: We were with the Prophet (ﷺ) on a journey and the Mu'adh-dhin (call maker for the prayer) wanted to pronounce the Adhan (call) for the Zuhr prayer. The Prophet (ﷺ) said, 'Let it become cooler." He again (after a while) wanted to pronounce the Adhan but the Prophet (ﷺ) said to him, "Let it become cooler till we see the shadows of hillocks."