§ Of Maeglin The Silmarillion

Then Eöl rode off in haste, and he was filled with hatred of all the Noldor; for he perceived now that Maeglin and Aredhel were fleeing to Gondolin. And driven by anger and the shame of his humiliation he crossed the Fords of Aros and rode hard upon the way that they had gone before; but though they knew not that he followed them, and he had the swiftest steed, he came never in sight of them until they reached the Brithiach, and abandoned their horses. Then by ill fate they were betrayed; for the horses neighed loudly, and Eöl's steed heard them, and sped towards them; and Eöl saw from afar the white raiment of Aredhel, and marked which way she went, seeking the secret path into the mountains.