All those wonders. The miracles wrought in Egypt are called nipheloth, "marvels," mophethim, "portents," and 'othoth, "signs." Mophethim, the word here used signifies something out of the ordinary course of nature, and corresponds to the Greek τέρατα and the Latin portenta.
It is a different word from that used in Exodus 3:20. In "all these wonders" are included, not only the three signs of Exodus 4:3-9, but the whole series of miracles afterwards wrought in Egypt, and glanced at in Exodus 3:20.
I will harden his heart. This expression, here used for the first time, and repeated so frequently in chs. 7-14; has given offence to many. Men, it is said, harden their own hearts against God; God does not actively interfere to harden the heart of anyone.
And this is so far true, that a special interference of God on the occasion, involving a supernatural hardening of Pharaoh's heart, is not to be thought of. But among the natural punishments which God has attached to sin, would seem to be the hardening of the entire nature of the man who sins.
If men "do not like to retain God in their knowledge, God gives them up to a reprobate mind" (Romans 1:28); if they resist the Spirit, he "takes his holy Spirit from them" (Psalms 51:11); if they sin against light he withdraws the light; if they stifle their natural affections of kindness, compassion and the like, it is a law of his providence that those affections shall wither and decay.
This seems to be the "hardening of the heart here intended—not an abnormal and miraculous interference with the soul of Pharaoh, but the natural effect upon his soul under God's moral government of those acts which he wilfully and wrongfully committed.