Thematic Bible: Firstborn set apart as a

You shall set apart to the Lord all that first opens the womb. All the firstlings of your livestock that are males shall be the Lord's. Every firstborn of a donkey you shall redeem by [substituting for it] a lamb, or if you will not redeem it, then you shall break its neck; and every firstborn among your sons shall you redeem. And when, in time to come, your son asks you, What does this mean? You shall say to him, By strength of hand the Lord brought us out from Egypt, from the house of bondage and bondmen. read more.
For when Pharaoh stubbornly refused to let us go, the Lord slew all the firstborn in the land of Egypt, both the firstborn of man and of livestock. Therefore I sacrifice to the Lord all the males that first open the womb; but all the firstborn of my sons I redeem. And it shall be as a reminder upon your hand or as frontlets between your eyes, for by a strong hand the Lord brought us out of Egypt.