21 The Lord said to Moses, "When you return to Egypt, see that you perform before Pharaoh all the wonders I have given you the power to do. But I will harden his heart so that he will not let the people go.

Matthew Henry's Commentary on Exodus 4:21

Commentary on Exodus 4:18-23

(Read Exodus 4:18-23)

After God had appeared in the bush, he often spake to Moses. Pharaoh had hardened his own heart against the groans and cries of the oppressed Israelites; and now God, in the way of righteous judgment, hardens his heart against the teaching of the miracles, and the terror of the plagues. But whether Pharaoh will hear, or whether he will forbear, Moses must tell him, Thus saith the Lord. He must demand a discharge for Israel, Let my son go; not only my servant, whom thou hast no right to detain, but my son. It is my son that serves me, and therefore must be spared, must be pleaded for. In case of refusal I will slay thy son, even thy first-born. As men deal with God's people, let them expect so to be dealt with.