Genesis 47:23-26

23Joseph said to the people, “Understand today that I have acquired you and your land for Pharaoh. Here is seed for you. Sow it in the land.

24At harvest, you are to give a fifth of it to Pharaoh, and four-fifths will be yours as seed for the field and as food for yourselves, your households, and your dependents.”

25“You have saved our lives,” they said. “We have found favor with our lord and will be Pharaoh’s slaves.”

26So Joseph made it a law, still in effect today in the land of Egypt, that a fifth of the produce belongs to Pharaoh. Only the priests’ land does not belong to Pharaoh.