Exodus 13:14-16

14“So when your son asks you in times to come, ‘What is this?’ say to him, ‘By a strong hand Adonai brought us out from Egypt, the house of bondage,

15and when Pharaoh refused to let us go, Adonai slew all the firstborn in the land of Egypt, both men and animals. So I sacrifice to Adonai all firstborn males, but I redeem the firstborn of my sons.’

16So it will be like a sign on your hand and like frontlets between your eyes, for by a strong hand Adonai brought us out of Egypt.”