§ Of the Beginning of Days The Silmarillion

And in that time of dark Yavanna also was unwilling utterly to forsake the Outer Lands; for all things teat grow are dear to her, and she mourned for the works that she had begun in Middle-earth but Melkor had marred. Therefore leaving the house of Aulë and the flowering meads of Valinor she would come at times and heal the hurts of Melkor; and returning she would ever urge the Valar to that war with his evil dominion that they must surely wage ere the coming of die Firstborn. And Oromë tamer of beasts would ride too at whiles in the darkness of the unlit forests; as a mighty hunter he came with spear and bow, pursuing to the death the monsters and fell creatures of the kingdom of Melkor, and his white horse Nahar shone like silver in the shadows. Then the sleeping earth trembled at the beat of his golden hooves, and in the twilight of the world Oromë would sound the Valaróma his great horn upon the plains of Arda; whereat the mountains echoed, and the shadows of evil fled away, and Melkor himself quailed in Utumno, foreboding the wrath to come. But even as Oromë passed the servants of Melkor would gather again; and the lands were filled with shadows and deceit.