Exodus 4:18-23

18Then Moses went back to his father-in-law, Jethro, and said to him, “Please let me return to my relatives in Egypt and see if they are still living.” Jethro said to Moses, “Go in peace.”

19Now in Midian the Lord told Moses, “Return to Egypt, for all the men who wanted to kill you are dead.”

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

21The Lord instructed Moses, “When you go back to Egypt, make sure you do before Pharaoh all the wonders that I have put within your power. But I will harden his heart so that he won’t let the people go.

22And you will say to Pharaoh: This is what the Lord says: Israel is my firstborn son.

23I told you: Let my son go so that he may worship me, but you refused to let him go. Look, I am about to kill your firstborn son!”