Exodus 13:15-16

New International Version

¹⁵ When Pharaoh stubbornly refused to let us go, the Lord killed the firstborn of both people and animals in Egypt. This is why I sacrifice to the Lord the first male offspring of every womb and redeem each of my firstborn sons.’^{(A) 16} And it will be like a sign on your hand and a symbol on your forehead^(B) that the Lord brought us out of Egypt with his mighty hand.”