(4) باب فِي وَقْتِ صَلاَةِ الظُّهْرِ
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.
Reference: Sunan Abi Dawud 399
In-book reference: Book 2, Hadith 9
English translation: Book 2, Hadith 399