§ Of the Beginning of Days The Silmarillion

Now therefore the Valar were gathered upon Almaren, fearing no evil, and because of the light of Illuin they did not perceive the shadow in the north that was cast from afar by Melkor; for he was grown dark as the Night of the Void. And it is sung that in that feast of the Spring of Arda Tulkas espoused Nessa the sister of Oromë, and she danced before the Valar upon the green grass of Almaren.