Genesis 47:23-26

23Joseph said to the people, “Now that I have bought you and your land today for Pharaoh, here is seed for you so you can plant the ground.

24But when the crop comes in, give a fifth of it to Pharaoh. The other four-fifths you may keep as seed for the fields and as food for yourselves and your households and your children.”

25“You have saved our lives,” they said. “May we find favor in the eyes of our lord; we will be in bondage to Pharaoh.”

26So Joseph established it as a law concerning land in Egypt—still in force today—that a fifth of the produce belongs to Pharaoh. It was only the land of the priests that did not become Pharaoh’s.