Exodus 4:21 MSG

[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. Then you are to tell Pharaoh, ‘God’s Message: Israel is my son, my firstborn! 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.’”