In The Children of Húrin:
On a time Húrin and Huor went with a company of scouts, but they were ambushed by the Orcs and scattered, and the brothers were pursued to the ford of Brithiach. There they would have been taken or slain but for the power of Ulmo that was still strong in the waters of Sirion; ...
In The Silmarillion, “Of the Ruin of Beleriand”:
But being with a company that was cut off from the rest they were pursued to the Ford of Brithiach, and there they would have been taken or slain but for the power of Ulmo, that was still strong in Sirion.