they swore an oath which none shall break , and none should take , by the name even of iluvatar , calling the everlasting dark upon them if they kept it not ; and manwe 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 .