Joseph collected all the food produced in those seven years of abundance in Egypt and stored it in the cities. In each city he put the food grown in the fields surrounding it.
So Joseph bought all the land in Egypt for Pharaoh. The Egyptians, one and all, sold their fields, because the famine was too severe for them. The land became Pharaoh’s,
However, he did not buy the land of the priests, because they received a regular allotment from Pharaoh and had food enough from the allotment Pharaoh gave them. That is why they did not sell their land.