Exodus 4:22-23 NIV

22 Then say to Pharaoh, 'This is what the LORD says: Israel is my firstborn son,1

References for Exodus 4:22

23 and I told you, "Let my son go,2 so he may worship3 me." But you refused to let him go; so I will kill your firstborn son.' "4

References for Exodus 4:23