Exodus 13:14-16

141And it shall be when your son asks you in time to come, saying, ‘What is this?’ then you shall say to him, ‘2With a 3powerful hand the Lord brought us out of Egypt, from the house of 4slavery. 15It came about, when Pharaoh was stubborn about letting us go, that the 5Lord 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 6offspring of every womb, but every firstborn of my sons I redeem.’ 16So 7it shall 8serve as a sign on your hand and as 9phylacteries 10on your forehead, for with a 11powerful hand the Lord brought us out of Egypt.”