Exodus 13:9-16

9It shall serve as a sign to you on your hand (arm), and as a reminder on your forehead, so that the instruction (law) of the Lord may be in your mouth; for with a strong and powerful hand the Lord brought you out of Egypt.

10Therefore, you shall keep this ordinance at this time from year to year.

11“Now it shall be when the Lord brings you into the land of the Canaanite, as He swore to you and your fathers, and gives it to you,

12you shall set apart and dedicate to the Lord all that first opens the womb. All the firstborn males of your livestock shall be the Lord’s.

13Every firstborn of a donkey you shall redeem by [substituting] a lamb [as a sacrifice for it], but if you do not [wish to] redeem it, then you shall break its neck; and every firstborn among your sons you shall redeem [that is, ‘buy back’ from God with a suitable sacrifice].

14And it shall be when your son asks you in time to come, saying, ‘What does this mean?’ you shall say to him, ‘With a strong and powerful hand the Lord brought us out of Egypt, from the house of bondage and slavery.

15For it happened, when Pharaoh stubbornly refused to let us go, that the Lord struck every firstborn in the land of Egypt, both the firstborn of man and the firstborn of animal. Therefore, I sacrifice to the Lord all the males, the first [to be born] of every womb, but every firstborn of my sons I redeem.’

16So it shall serve as a sign and a reminder on your [left] hand (arm) and as frontlets between your eyes, for by a strong and powerful hand the Lord brought us out of Egypt.”