He hardened Pharaoh’s heart. — This is a mis-translation. The verb is intransitive, and “Pharaoh’s heart” is its nominative case. Translate, “Pharaoh’s heart hardened itself.” It is essential to the idea of a final penal hardening that in the earlier stages Pharaoh should have been left to himself.
That he hearkened not. — Heb., and he hearkened not.
As the Lord had said. — See above, Exodus 3:19; Exodus 7:4