§ Of the Ruin of Doriath The Silmarillion

But when Húrin was gone from Menegroth, Thingol sat long in silence, gazing upon the great treasure that lay upon his knees; and it came into his mind that it should be remade, and in it should be set the Silmaril. For as the years passed Thingol's thought turned unceasingly to the jewel of Fëanor, and became bound to it, and he liked not to let it rest even behind the doors of his inmost treasury; and he was minded now to bear it with him always, waking and sleeping.