It is narrated from Sayyiduna Jabir bin Abdullah (may Allah be pleased with him), he says: I used to perform the Zuhr prayer with the Messenger of Allah (peace and blessings be upon him), and due to the intensity of the heat, I would take a handful of pebbles in my palm so that they would cool down and then I could prostrate on them. In another narration it is stated: Due to the intensity of the heat, I would transfer them to the other hand so that they would cool down.