Exodus 13:14-17

14And when in time to come your son asks you, ‘What does this mean?’ you shall say to him, ‘By a strong hand the LORD brought us out of Egypt, from the house of slavery. 15For when Pharaoh stubbornly refused to let us go, the LORD killed all the firstborn in the land of Egypt, both the firstborn of man and the firstborn of animals. Therefore I sacrifice to the LORD all the males that first open the womb, but all the firstborn of my sons I redeem.’ 16It shall be as a mark on your hand or frontlets between your eyes, for by a strong hand the LORD brought us out of Egypt.” 17When Pharaoh let the people go, God did not lead them by way of the land of the Philistines, although that was near. For God said, “Lest the people change their minds when they see war and return to Egypt.”