21 And the Lord said to Moses, “When you go back to Egypt, see that you do before Pharaoh all the ^amiracles that I have put in your power. But ^bI will harden his heart, so that he will not let the people go. 22 Then you shall say to Pharaoh, ‘Thus says the Lord, ^cIsrael is my ^dfirstborn son, 23 and I say to you, “Let my son go that he may serve me.” If you refuse to let him go, behold, I ^ewill kill your firstborn son.’”