Exodus 8:19

The finger of God. — Rather, of a goal. The magicians meant to say, “This is beyond the power of man: it is supernatural; some god must be helping Moses and Aaron.” They did not mean to profess a belief in One God.

Pharaoh’s heart was hardened. — The mosquitoes did not impress Pharaoh as the frogs had done (Exodus 8:8). His heart remained hard. He had no need to harden it by an act of his will. Probably the visitation affected him but little, since he would possess mosquito curtains, and could inhabit the loftier parts of his palace, which would be above the height whereto the mosquito ascends (Herod, ii. 95).