It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that we used to pray with the Messenger of Allah (peace and blessings be upon him) in intense heat, and when one of us was unable to place his forehead on the ground, he would spread out his garment and prostrate on it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2665