§ Of the Noldor in Beleriand The Silmarillion

And Ulmo warned Turgon that he also lay under the Doom of Mandos, which Ulmo had no power to remove. 'Thus it may come to pass,' he said, 'that the curse of the Noldor shall find thee too ere the end, and treason awake within thy walls. Then they shall be in peril of fire. But if this peril draweth nigh indeed, then even from Nevrast one shall come to warn thee, and from him beyond ruin and fire hope shall be born for Elves and Men. Leave therefore in this house arms and a sword, that in years to come he may find them, and thus shalt thou know him, and not be deceived.' And Ulmo declared to Turgon of what kind and stature should be the helm and mail and sword that he left behind.