Musannaf Ibn Abi Shayba 3:390

Abu Bakr narrated to us, he said: Jarir narrated to us, from Mansur, from Fudayl, from Ibrahim, who said: Umar prayed Jumu'ah with the people one day on a day of intense cold. He cast the edge of his garment onto the ground and began to prostrate upon it. Then he said: "O people, if one of you experiences heat or cold, let him prostrate upon the edge of his garment."