Exodus 13:13-17

But every firstborn of a donkey you shall redeem with a lamb, but if you do not redeem it, then you shall break its neck; and every firstborn among your sons you shall redeem.

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

And it came about, when Pharaoh was stubborn about letting us go, that the Lord put to death every firstborn in the land of Egypt, from human firstborns to animal firstborns. Therefore, I sacrifice to the Lord the males, every firstborn of a womb, but every firstborn of my sons I redeem.’

So it shall serve as a sign on your hand and as phylacteries on your forehead, for with a powerful hand the Lord brought us out of Egypt.” God Leads the People

Now when Pharaoh had let the people go, God did not lead them by the way of the land of the Philistines, even though it was near; for God said, “The people might change their minds when they see war, and return to Egypt.”