It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that when we used to pray with the Messenger of Allah (peace and blessings be upon him), and one of us was unable to place his forehead on the ground because of the intensity of the heat, he would spread out his garment and prostrate on it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2663