Hadith #158 (Jami' al-Tirmidhi)
Book: The Book on Salat (Prayer)
Narrator(s): Abu Dharr al-Ghaffari, Mahmud bin Ghaylan محمود بن غيلان العدوي مولاهم أبو أحمد, Mhajr Abu al-Hasan al-Tymy مهاجر أبو الحسن التيمي, Shu'bah bin al-Hajjaj شعبة بن الحجاج, Sulaiman bin Da'ud bin al-Jarud سليمان بن داود أبو داود الطيالسي, Zayd bin Wahb al-Jhny زيد بن وهب الجهني

“Allah’s Messenger was on a journey and Bilal was with him. So he wanted to call for the prayer, but he (the Prophet) said: ‘Let it get cooler.’ Then he wanted to call for the prayer, so Allah’s Messenger said: ‘Let it get to the cooler time of Zuhr.'” He (i.e., Abu Dharr) said: “Until we saw the shadows of the hillocks, then he commanded that the Iqamah be called and then led the people in prayer. Allah’s Messenger said: ‘The severity of heat is from the raging of Hell, so wait until it becomes cooler for the (Zuhr) prayer.'”

Source: https://parallelquran.com/hadith/jami-al-tirmidhi-158/