وَعَنْ أَنَسٍ قَالَ: كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا اشْتَدَّ الْبَرْدُ بَكَّرَ بِالصَّلَاةِ وَإِذَا اشْتَدَّ الْحَرُّ أَبْرَدَ بِالصَّلَاةِ. يَعْنِي الْجُمُعَةَ. رَوَاهُ البُخَارِيّ
Anas said that when it was very cold the Prophet observed the prayer early, and when it was very hot he delayed the prayer till it was cooler. The reference is to the Friday prayer. Bukhari transmitted it.