Gandalf: You cannot pass! Frodo: Gandalf! Gandalf: I am a servant of the Secret Fire, wielder of the flame of Anor. Go back to the shadow. The dark fire will not avail you, flame of Udun! You shall not pass!
Gandalf the Grey fights the Balrog on the Bridge of Khazad-dûm in the Mines of Moria, in an attempt to allow the Fellowship of the Ring to escape.