Things of Middle-earth
Oath of Fëanor
The oath to reclaim the Silmarils, vowed by Fëanor and his sons after Morgoth slew his father, Finwë, and stole the jewels from them; trigger for the three Kinslayings:
They swore an oath which none shall break, and none should take, by the name even of Ilúvatar, calling the Everlasting Dark upon them if they kept it not; and Manwë they named in witness, and Varda, and the hallowed mountain of Taniquetil, vowing to pursue with vengeance and hatred to the ends of the World Vala, Demon, Elf or Man as yet unborn, or any creature, great or small, good or evil, that time should bring forth unto the end of days, whoso should hold or take or keep a Silmaril from their possession....
[Many] quailed to hear the dread words. For so sworn, good or evil, an oath may not be broken, and it shall pursue oathkeeper and oathbreaker to the world's end.
The Silmarillion, Quenta Silmarillion, Ch 9, Of the Flight of the Noldor
Be he foe or friend, be he foul or clean,
brood of Morgoth or bright Vala,
Elda or Maia or Aftercomer,
Man yet unborn upon Middle-earth,
neither law, nor love, nor league of swords,
dread nor danger, not Doom itself,
shall defend him from Fëanor, and Fëanor's kin,
whoso hideth or hoardeth, or in hand taketh,
finding keepeth or afar casteth
a Silmaril. This swear we all:
death we will deal him ere Day's ending,
woe unto world's end! Our word hear thou,
Eru Allfather! To the everlasting
Darkness doom us if our deed faileth.
On the holy mountain hear in witness
and our vow remember, Manwë and Varda!
Morgoth's Ring, HoME Vol 10, Part 2, The Annals of Aman
Contributors: Elena Tiriel 5Nov09