Yeshayah 27:1

In Yom Hahu HASHEM with His cherev hakashah v'hagedolah v'hachazakah (terrible and great and strong sword) shall punish Leviathan the Nachash bari'ach (fleeing serpent), even Leviathan that Nachash akallaton (crooked serpent); and He shall slay the Tanin (serpent, devouring sea monster) that is in the sea.