18 Moses went back to Jethro his father-in-law and said, "I need to return to my relatives who are in Egypt. I want to see if they're still alive." Jethro said, "Go. And peace be with you." 19 God said to Moses in Midian: "Go. Return to Egypt. All the men who wanted to kill you are dead." 20 So Moses took his wife and sons and put them on a donkey for the return trip to Egypt. He had a firm grip on the staff of God. 21 God said to Moses, "When you get back to Egypt, be prepared: All the wonders that I will do through you, you'll do before Pharaoh. But I will make him stubborn so that he will refuse to let the people go. 22 Then you are to tell Pharaoh, 'God's Message: Israel is my son, my firstborn! 23 I told you, "Free my son so that he can serve me." But you refused to free him. So now I'm going to 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.