I would offer my noon prayer with the Messenger of Allah ﷺ and took a handful of gravels so that they might become cold in my hand and I placed them (before me) so that I may put my forehead on them at the time when I would prostrate. I did this due to the intensity of heat. (Using translation from Abū Dāʾūd 399)
كُنْتُ أُصَلِّي مَعَ رَسُولِ اللهِ ﷺ الظُّهْرَ فَآخُذُ قَبْضَةً مِنْ حَصًى فِي كَفِّي لِتَبْرُدَ حَتَّى أَسْجُدَ عَلَيْهِ مِنْ شِدَّةِ الْحَرِّ