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.'"
24 On the journey back, as they camped for the night, God met Moses and would have killed him but 25 Zipporah took a flint knife and cut off her son's foreskin, and touched Moses' member with it. She said, "Oh! You're a bridegroom of blood to me!" 26 Then God let him go. She used the phrase "bridegroom of blood" because of the circumcision.
Matthew Henry's Commentary on Exodus 4:18-26
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.
Commentary on Exodus 4:24-31
(Read Exodus 4:24-31)
God met Moses in anger. The Lord threatened him with death or sent sickness upon him, as the punishment of his having neglected to circumcise his son. When God discovers to us what is amiss in our lives, we must give all diligence to amend it speedily. This is the voice of every rod; it calls us to return to Him that smites us. God sent Aaron to meet Moses. The more they saw of God's bringing them together, the more pleasant their interview was. The elders of Israel met them in faith, and were ready to obey them. It often happens, that less difficulty is found than was expected, in such undertakings as are according to the will of God, and for his glory. Let us but arise and try at our proper work, the Lord will be with us and prosper us. If Israel welcomed the tidings of their deliverance, and worshipped the Lord, how should we welcome the glad tidings of redemption, embrace it in faith, and adore the Redeemer!