Sahih Muslim
Sahih Muslim 615 e
The recommendation to delay Zuhr (until it has cooled down) in severe heat for one who finds it too hot in route to join the congregation
Arabic hadith text
حَدَّثَنَا ابْنُ رَافِعٍ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، حَدَّثَنَا مَعْمَرٌ، عَنْ هَمَّامِ بْنِ مُنَبِّهٍ، قَالَ هَذَا مَا حَدَّثَنَا أَبُو هُرَيْرَةَ، عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم فَذَكَرَ أَحَادِيثَ مِنْهَا وَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم "أَبْرِدُوا عَنِ الْحَرِّ فِي الصَّلاَةِ فَإِنَّ شِدَّةَ الْحَرِّ مِنْ فَيْحِ جَهَنَّمَ "
Translation
Hammam b. Munabbih reported
This is what Abu Huraira narrated to us from the Prophet and he transmitted some ahadith-one of them was that the Messenger of Allah (ﷺ) said: Let the heat become less severe before prayer, for the intensity of heat is from the exhalation of Hell.