Exodus 4:20-26

20So Moses took his wife and his sons, set them on a donkey and returned to the land of Egypt. Moses took the staff of God in his hand.

21Adonai said to Moses, “When you go back to Egypt, see that you do all the wonders before Pharaoh that I have put in your hand. Still, I will harden his heart, and he will not let the people go.

22You are to say to Pharaoh, “This is what Adonai says: ‘Israel is My son, My firstborn.

23So I have said to you, Let My son go, that he may serve Me, but you have refused to let him go. Behold, I will slay your son, your firstborn.’”

24It happened along the way, at a lodging place, that Adonai met him and sought to kill him!

25But Zipporah took a flint, cut off the foreskin of her son, and threw it at his feet, saying, “You are surely a bridegroom of blood to me.”

26She said, “A bridegroom of blood” because of the circumcision. Then He let him alone.