C. F. Keil and Franz Delitzsch on Genesis 47:22

Gen 47:22

The lands of the priests Joseph did not buy, “for the priests had an allowance from Pharaoh, and ate their allowance, which Pharaoh gave them; therefore they sold not their lands.” חק a fixed allowance of food, as in Pro 30:8; Eze 16:27. This allowance was granted by Pharaoh probably only during the years of famine; in any case it was an arrangement which ceased when the possessions of the priests sufficed for their need, since, according to Diod. Sic. i. 73, the priests provided the sacrifices and the support of both themselves and their servants from the revenue of their lands; and with this Herodotus also agrees (2, 37).