John Calvin Commentary Exodus 9:7

"And Pharaoh sent, and, behold, there was not so much as one of the cattle of the Israelites dead. But the heart of Pharaoh was stubborn, and he did not let the people go." — Exodus 9:7 (ASV)

And Pharaoh sent. I leave it undecided whether he first sent these inspectors at that time.¹⁰⁴ It may be that, in the blindness of his obstinacy, he neglected this until he was reminded by Moses.

For we know how the reprobate shut their eyes against the manifest marks of God’s wrath and willfully indulge in their errors.

Certainly, there is no doubt that Pharaoh, while he sought to harden himself in every way, deliberately ignored what was very useful for him to know. But, since he was informed by Moses of the distinction between the Egyptians and the Israelites, he was compelled, whether he willed it or not, to ascertain from actual inspection what he would have gladly remained ignorant of.

But this was no obscure demonstration of God’s paternal favor towards his chosen people: the contagion did not affect that part of Egypt which was most full of cattle, though it ravaged the whole surrounding neighborhood.

Therefore, the hardness of the king’s wicked heart was all the more base and astonishing, since he was not moved even by this extraordinary circumstance. For it was a sign of horrible folly that, when the matter was examined and discovered by his subordinates, he still hardened his heart and would not obey God.

¹⁰⁴ “It is asked, why he did not do so before? Resp., Because either, first, The roads were impassable on account of the frogs, lice, etc.; or , The roads were impassable on account of the frogs, lice, etc.; or secondly, It did not previously occur to him.” —, It did not previously occur to him.” — Menochius in Pol. Syn.