Genesis 47:23-26

23And Joseph said to the people, Behold, I have bought you this day and your land for Pharaoh: lo, here is seed for you, and sow the land.

24And it shall come to pass in the increase that ye shall give the fifth to Pharaoh, and the four parts shall be your own, for seed of the field, and for your food, and for them of your households, and for food for your little ones.

25And they said, Thou hast saved us alive. Let us find favour in the eyes of my lord, and we will be Pharaoh's bondmen.

26And Joseph made it a law over the land of Egypt to this day, [that] the fifth should be for Pharaoh, except the land of the priests: theirs alone did not become Pharaoh's.