Numbers 35:4-6

New Revised Standard Version Catholic Edition

⁴ The pasture lands of the towns, which you shall give to the Levites, shall reach from the wall of the town outward a thousand cubits all around. ⁵ You shall measure, outside the town, for the east side two thousand cubits, for the south side two thousand cubits, for the west side two thousand cubits, and for the north side two thousand cubits, with the town in the middle; this shall belong to them as pasture land for their towns.

⁶ The towns that you give to the Levites shall include the six cities of refuge, where you shall permit a slayer to flee, and in addition to them you shall give forty-two towns.