Numbers 35:4-5

35:4 The grazing lands around the towns that you will give to the Levites must extend to a distance of 500 yards from the town wall.

35:5 “You must measure from outside the wall of the town on the east 1,000 yards, and on the south side 1,000 yards, and on the west side 1,000 yards, and on the north side 1,000 yards, with the town in the middle. This territory must belong to them as grazing land for the towns.