Exodus 4:21-23 ▼

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

22 You shall tell Pharaoh, ‘Yahweh says, Israel is my son, my firstborn,

23 and I have said to you, “Let my son go, that he may serve me;” and you have refused to let him go. Behold, I will kill your firstborn son.’”