Exodus 13:12-15

¹²you are to set aside the first birth out of every womb to GOD. Every first birth from your livestock belongs to GOD.

¹³You can redeem every first birth of a donkey if you want to by substituting a lamb; if you decide not to redeem it, you must break its neck. "Redeem every firstborn child among your sons.

¹⁴When the time comes and your son asks you, "What does this mean?'' you tell him, "GOD brought us out of Egypt, out of a house of slavery, with a powerful hand.

¹⁵When Pharaoh stubbornly refused to let us go, GOD killed every firstborn in Egypt, the firstborn of both humans and animals. That''s why I make a sacrifice for every first male birth from the womb to GOD and redeem every firstborn son.''