Numbers 35:2-4

2“Command the children of Israel that they give the Levites cities to dwell in from the inheritance of their possession, and you shall also give the Levites common-land around the cities.

3They shall have the cities to dwell in; and their common-land shall be for their cattle, for their herds, and for all their animals.

4The common-land of the cities which you will give the Levites shall extend from the wall of the city outward a thousand cubits all around.