Narrated Jabir ibn Abdullah:

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.

حَدَّثَنَا أَحْمَدُ بْنُ حَنْبَلٍ، وَمُسَدَّدٌ، قَالاَ حَدَّثَنَا عَبَّادُ بْنُ عَبَّادٍ، حَدَّثَنَا مُحَمَّدُ بْنُ عَمْرٍو، عَنْ سَعِيدِ بْنِ الْحَارِثِ الأَنْصَارِيِّ، عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ، قَالَ كُنْتُ أُصَلِّي الظُّهْرَ مَعَ رَسُولِ اللَّهِ ﷺ فَآخُذُ قَبْضَةً مِنَ الْحَصَى لِتَبْرُدَ فِي كَفِّي أَضَعُهَا لِجَبْهَتِي أَسْجُدُ عَلَيْهَا لِشِدَّةِ الْحَرِّ .