"Bearskin" is a fairy tale collected by the Brothers Grimm, as tale no. 101.

A man was a soldier, but when war ended, his parents were dead, and his brothers had no place for him. - A green-coated man with a cloven hoof appeared to him and offered to make him rich if he would for seven years not cut his hair, clip his nails, bathe, or pray, and wear a coat and cloak that he would give him. At the end, if he survived, he would be rich and free. If he died during the time, the devil would have him. The desperate soldier agreed and the devil gave him the green coat telling him he would find its pockets always full of limitless money and then a bearskin, telling him that he must sleep in it and would be known as Bearskin because of it...