18 So Moses went and returned to Jethro his father-in-law, and said to him, "Please let me go and return to my brethren who are in Egypt, and see whether they are still alive." And Jethro said to Moses, "Go in peace." 19 And the Lord said to Moses in Midian, "Go, return to Egypt; for all the men who sought your life are dead." 20 Then Moses took his wife and his sons and set them on a donkey, and he returned to the land of Egypt. And Moses took the rod of God in his hand. 21 And the Lord said to Moses, "When you go back to Egypt, see that you do all those wonders before Pharaoh which I have put in your hand. But I will harden his heart, so that he will not let the people go. 22 Then you shall say to Pharaoh, 'Thus says the Lord: "Israel is My son, My firstborn. 23 So I say to you, let My son go that he may serve Me. But if you refuse to let him go, indeed I will kill your son, your firstborn." ' "
Matthew Henry's Commentary on Exodus 4:18-23
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.