highway - free communication, resting on the highest basis, the common faith of both (Isa 19:18; Isa 11:16). Assyria and Egypt were joined under Alexander as parts of his empire: Jews and proselytes from both met at the feasts of Jerusalem. A type of gospel times to come.
serve with - serve Jehovah with the Assyrians. So “serve” is used absolutely (Job 36:11).