Volume 1, Book 11, Number 602:
Narrated Abu Dhar:
We were in the company of the Prophet on a journey and the Mu’adhdhin wanted to pronounce
the Adhan for the (Zuhr) prayer. The Prophet said to him, “Let it become cooler.” Then he again
wanted to pronounce the Adhan but the Prophet; said to him, “Let it become cooler.” The Mu’adh-
dhin again wanted to pronounce the Adhan for the prayer but the Prophet said, “Let it become cool –
er,” till the shadows of the hillocks become equal to their sizes. The Prophet added, “The severity of
the heat is from the raging of Hell.”