Exodus 13:12-16

12you must present all firstborn sons and firstborn male animals to the Lord, for they belong to him.

13A 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.

14“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.

15Pharaoh stubbornly refused to let us go, so the Lord killed all the firstborn males throughout the land of Egypt, both people and animals. That is why I now sacrifice all the firstborn males to the Lord—except that the firstborn sons are always bought back.’

16This ceremony will be like a mark branded on your hand or your forehead. It is a reminder that the power of the Lord’s mighty hand brought us out of Egypt.”