Exodus 13:12-16

121you shall 2devote to the Lord the first 3offspring of every womb, and 4the first offspring of every beast that you own; the males belong to the Lord. 13But 5every first 6offspring of a donkey you shall redeem with a lamb, but if you do not redeem it, then you shall break its neck; and 7every firstborn of man among your sons you shall redeem. 148And it shall be when your son asks you in time to come, saying, ‘What is this?’ then you shall say to him, ‘9With a 10powerful hand the Lord brought us out of Egypt, from the house of 11slavery. 15It came about, when Pharaoh was stubborn about letting us go, that the 12Lord killed every firstborn in the land of Egypt, both the firstborn of man and the firstborn of beast. Therefore, I sacrifice to the Lord the males, the first 13offspring of every womb, but every firstborn of my sons I redeem.’ 16So 14it shall 15serve as a sign on your hand and as 16phylacteries 17on your forehead, for with a 18powerful hand the Lord brought us out of Egypt.”