§ Of the Silmarils and the Unrest of the Noldor The Silmarillion

Now the unrest of the Noldor was not indeed hidden from the Valar, but its seed had been sown in the dark; and therefore, since Fëanor first spoke openly against them, they judged that he was the mover of discontent, being eminent in self-will and arrogance, though all the Noldor had become proud. And Manwë was grieved, but he watched and said no word. The Valar had brought the Eldar to their land freely, to dwell or to depart; and though they might judge departure to be folly, they might not restrain them from it. But now the deeds of Fëanor could not be passed over, and the Valar were angered and dismayed; and he was summoned to appear before them at the gates of Valmar, to answer for all his words and deeds. There also were summoned all others who had any part in this matter, or any knowledge of it; and Fëanor standing before Mandos in the Ring of Doom was commanded to answer all that was asked of him. Then at last the root was laid bare, and the malice of Melkor revealed; and straightway Tulkas left the council to lay hands upon him and bring him again to judgement. But Fëanor was not held guiltless, for he it was that had broken the peace of Valinor and drawn his sword upon his kinsman; and Mandos said to him: 'Thou speakest of thraldom. If thraldom it be, thou canst not escape it; for Manwë is King of Arda, and not of Aman only. And this deed was unlawful, whether in Aman or not in Aman. Therefore this doom is now made: for twelve years thou shall leave Tirion where this threat was uttered. In that time take counsel with thyself, and remember who and what thou art. But after that time this matter shall be set in peace and held redressed, if others will release thee.'