Adam Clarke on Exodus 7:13

And he hardened Pharaoh's heart - ויחזק לב פרעה vaiyechezak leb Paroh, "And the heart of Pharaoh was hardened," the identical words which in Exo 7:22 are thus translated, and which should have been rendered in the same way here, lest the hardening, which was evidently the effect of his own obstinate shutting of his eyes against the truth, should be attributed to God. See Clarke's note on Exo 4:21.