Still, Pharaoh’s heart was hardened, and he would not listen to them, just as the LORD had said.
The first time that Moses made his application to Pharaoh, he produced his instructions only; now he is directed to produce his credentials, and does accordingly. 1. It is taken for granted that Pharaoh would challenge these demandants to work a miracle, that, by a performance evidently above the power of nature, they might prove their commission from the God of nature.
Commenting on Exodus 7:8-13
And he hardened Pharaoh's heart,.... Or, "notwithstanding the heart of Pharaoh was hardened" (a); though he saw the rods of his magicians devoured by rod; or "therefore" (b) his heart was hardened, because he saw that the rods of his magicians became serpents as well as Aaron's; in which there was a deception of sight, and which was suffered for the hardening of his heart...
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.