Exodus 13:11-14

“This is what you must do when the LORD fulfills the promise he swore to you and to your ancestors. When he gives you the land where the Canaanites now live, you must present all firstborn sons and firstborn male animals to the LORD, for they belong to him. A firstborn donkey may be bought back from the LORD by presenting a lamb or young goat in its place. But if you do not buy it back, you must break its neck. However, you must buy back every firstborn son. “And in the future, your children will ask you, ‘What does all this mean?’ Then you will tell them, ‘With the power of his mighty hand, the LORD brought us out of Egypt, the place of our slavery.