Sahih al-Bukhari 9:13
Narrated Abu Dhar:
The Mu'adh-dhin (call-maker) of the Prophet (ﷺ) pronounced the Adhan (call) for the Zuhr prayer but the Prophet said, "Let it be cooler, let it be cooler." Or said, 'Wait, wait, because the severity of heat is from the raging of the Hell-fire. In severe hot weather, pray when it becomes (a bit) cooler and the shadows of hillocks appear."
Reference
Sahih al-Bukhari 9:13
In-book reference
Book 9, Hadith 13
Arabic Text
حَدَّثَنَا ابْنُ بَشَّارٍ، قَالَ حَدَّثَنَا غُنْدَرٌ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنِ الْمُهَاجِرِ أَبِي الْحَسَنِ، سَمِعَ زَيْدَ بْنَ وَهْبٍ، عَنْ أَبِي ذَرٍّ، قَالَ أَذَّنَ مُؤَذِّنُ النَّبِيِّ صلى الله عليه وسلم الظُّهْرَ فَقَالَ " أَبْرِدْ أَبْرِدْ ـ أَوْ قَالَ ـ انْتَظِرِ انْتَظِرْ ". وَقَالَ " شِدَّةُ الْحَرِّ مِنْ فَيْحِ جَهَنَّمَ، فَإِذَا اشْتَدَّ الْحَرُّ فَأَبْرِدُوا عَنِ الصَّلاَةِ ". حَتَّى رَأَيْنَا فَىْءَ التُّلُولِ.