Sunan Ibn Majah 680
It was narrated that Mughirah bin Shu'bah said:
We were praying Zuhr with the Messenger of Allah at the time of intense heat (i.e., midday when the sun has just passed its zenith) and he said to us, "Wait for it to cool down before you pray, for intense heat is from the flaring up of the Hell-fire."
حَدَّثَنَا تَمِيمُ بْنُ الْمُنْتَصِرِ الْوَاسِطِيُّ، حَدَّثَنَا إِسْحَاقُ بْنُ يُوسُفَ، عَنْ شَرِيكٍ، عَنْ بَيَانٍ، عَنْ قَيْسِ بْنِ أَبِي حَازِمٍ، عَنِ الْمُغِيرَةِ بْنِ شُعْبَةَ، قَالَ كُنَّا نُصَلِّي مَعَ رَسُولِ اللَّهِ ـ صلى الله عليه وسلم ـ صَلاَةَ الظُّهْرِ بِالْهَاجِرَةِ فَقَالَ لَنَا ‏
"‏ أَبْرِدُوا بِالصَّلاَةِ فَإِنَّ شِدَّةَ الْحَرِّ مِنْ فَيْحِ جَهَنَّمَ ‏"‏ ‏.‏