§ Of Beren and Lúthien The Silmarillion

Thus Beren came before King Finrod Felagund; and Felagund knew him, needing no ring to remind him of the kin of Bëor and of Barahir. Behind closed doors they sat, and Beren told of the death of Barahir, and of all that had befallen him in Doriath; and he wept, recalling Lúthien and their joy together. But Felagund heard his tale in wonder and disquiet; and he knew that the oath he had sworn was come upon him for his death, as long before he had foretold to Galadriel. He spoke then to Beren in heaviness of heart. 'It is plain that Thingol desires your death; but it seems that this doom goes beyond his purpose, and that the Oath of Fëanor is again at work. For the Silmarils are cursed with an oath of hatred, and he that even names them in desire moves a great power from slumber; and the sons of Fëanor would lay all the Elf-kingdoms in ruin rather than suffer any other than themselves to win or possess a Silmaril, for the Oath drives them. And now Celegorm and Curufin are dwelling in my halls; and though I, Finarfin's son, am King, they have won a strong power in the realm, and lead many of their own people. They have shown friendship to me in every need, but I fear that they will show neither love nor mercy to you, if your quest be told. Yet my own oath holds; and thus we are all ensnared.'