Well, Captain Farrell would be English, so there'd be no point in talking to him with any sort of heavenly language. I've got something that seems to make sense to me (given the circumstances):

"Push your ring, dummer do, dumb or die."

That would be, "Shove your ring over here dumb person, remain dumb or you'll die..."

If you push your ring off your finger you hand is outstretched and in full view. If you pull your ring off your finger your hands are crooked and close to your body and may be concealing something, or may quickly grab a weopon from inside your clothing.

Roadside arguments, and pleas for clemency were the bane of a highwayman's life, hence silence was a requirement (in this case anyway). A dumber or dummer was a mute person in those days.