Now ¹  in Egypt the Midianites ²  sold Joseph ³  to Potiphar, one of Pharaoh’s officials, the captain of the guard. ⁴ 

So Joseph bought all the land of Egypt for Pharaoh. Each ¹  of the Egyptians sold his field, for the famine was severe. ²  So the land became Pharaoh’s.

But he did not purchase the land of the priests because the priests had an allotment from Pharaoh and they ate from their allotment that Pharaoh gave them. That is why they did not sell their land.