Exodus 4:21-23

New Catholic Bible

²¹ The Lord said to Moses, “When you return to Egypt, see that you do all the signs that I have placed in your hand in the presence of Pharaoh. But I will harden his heart and he will not let my people go. ²² You will say to Pharaoh, ‘Thus says the Lord: “Israel is my firstborn son. ²³ I have told you to let my son go so that he might serve me, but you have refused to let him leave. Therefore, I will kill your firstborn son.” ’ ”