Exodus 4:21-23

International Standard Version

²¹ Then the Lord told Moses, “When you set out to return to Egypt, keep in mind^[a] all the wonders that I’ve put in your power,^[b] so that you may do them before Pharaoh. But I’ll harden his heart so that he won’t let the people go. ²² You are to say to Pharaoh, ‘This is what the Lord says: “Israel is my firstborn son. ²³ And I say to you, ‘Let my son go so he may serve me. If you refuse to let him go, then I will kill your firstborn son.’”’”