Exodus:4:22-23
web@Exodus:4:22 @ You shall tell Pharaoh, 'Thus says Yahweh, Israel is my son, my firstborn,
web@Exodus:4:23 @ 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 son, your firstborn.'"