§ Of Beren and Lúthien The Silmarillion

Thereafter for four years more Beren wandered still upon Dorthonion, a solitary outlaw; but he became the friend of birds and beasts, and they aided him, and did not betray him, and from that time forth he ate no flesh nor slew any living thing that was not in the service of Morgoth. He did not fear death, but only captivity, and being bold and desperate he escaped both death and bonds; and the deeds of lonely daring that he achieved were noised abroad throughout Beleriand, and the tail of them came even into Doriath. At length Morgoth set a price upon his head no less than the price upon the head of Fingon, High King of the Noldor; but the Orcs fled rather at the rumour of his approach than sought him out. Therefore and army was sent against him under the command of Sauron; and Sauron brought werewolves, fell beasts inhabited by dreadful spirits that he had imprisoned in their bodies.