كتاب الْمَسَاجِدِ وَمَوَاضِعِ الصَّلاَةِ
5  
The Book of Mosques and Places of Prayer
(32)
Chapter: 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
(32)
باب اسْتِحْبَابِ الإِبْرَادِ بِالظُّهْرِ فِي شِدَّةِ الْحَرِّ لِمَنْ يَمْضِي إِلَى جَمَاعَةٍ وَيَنَالُهُ الْحَرُّ فِي طَرِيقِهِ
Sahih Muslim 615 a

Abu Huraira reported that the Messenger of Allah (may peace he upon him) said:

When it is very hot, say (the noon prayer) when the extreme heat passes away, for intensity of heat is from the exhalation of Hell.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا لَيْثٌ، ح وَحَدَّثَنَا مُحَمَّدُ بْنُ رُمْحٍ، أَخ ْبَرَنَا اللَّيْثُ، عَنِ ابْنِ شِهَابٍ، عَنِ ابْنِ الْمُسَيَّبِ، وَأَبِي، سَلَمَةَ بْنِ عَبْدِ الرَّحْمَنِ عَنْ أَبِي هُرَيْرَةَ، أَنَّهُ قَالَ إِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ إِذَا اشْتَدَّ الْحَرُّ فَأَبْرِدُوا بِالصَّلاَةِ فَإِنَّ شِدَّةَ الْحَرِّ مِنْ فَيْحِ جَهَنَّمَ ‏"‏ ‏.‏
Reference : Sahih Muslim 615a
In-book reference : Book 5, Hadith 229
USC-MSA web (English) reference : Book 4, Hadith 1282
  (deprecated numbering scheme)