[Machine] I used to pray the Dhuhr prayer with the Messenger of Allah ﷺ , and I would take a handful of pebbles in my hand until they cooled down, and I would place them on my forehead when I prostrated due to the intensity of the heat. The sheikh (may Allah have mercy on him) said, "Even if it was permissible to prostrate on a garment that was connected to the pebbles, it would be easier than cooling the pebbles in the hand and placing them to prostrate on them. And with Allah is the success.  

كُنْتُ أُصَلِّي مَعَ رَسُولِ اللهِ ﷺ صَلَاةَ الظُّهْرِ فَآخُذُ قَبْضَةً مِنَ الْحَصَى فِي كَفِّي حَتَّى تَبْرُدَ وَأَضَعُهَا بِجَبْهَتِي إِذَا سَجَدْتُ مِنْ شِدَّةِ الْحَرِّ قَالَ الشَّيْخُ رَحِمَهُ اللهُ وَلَوْ جَازَ السُّجُودُ عَلَى ثَوْبٍ مُتَّصِلٍ بِهِ لَكَانَ ذَلِكَ أَسْهَلَ مِنْ تَبْرِيدِ الْحَصَا فِي الْكَفِّ وَوَضْعِهَا لِلسُّجُودِ عَلَيْهَا وَبِاللهِ التَّوْفِيقُ