Numbers 35:9

5 You are also to measure two thousand cubits outside the city on the east, two thousand on the south, two thousand on the west, and two thousand on the north, with the city in the center. These areas will serve as larger pasturelands for the cities.

6 Six of the cities you give the Levites are to be appointed as cities of refuge, to which a manslayer may flee. In addition to these, give the Levites forty-two other cities.

7 The total number of cities you give the Levites will be forty-eight, with their corresponding pasturelands.

8 The cities that you apportion from the territory of the Israelites should be given to the Levites in proportion to the inheritance of each tribe: more from a larger tribe and less from a smaller one.”

9 Then the LORD said to Moses,

10 “Speak to the Israelites and tell them: When you cross the Jordan into the land of Canaan,

11 designate cities to serve as your cities of refuge, so that a person who kills someone unintentionally may flee there.

12 You are to have these cities as a refuge from the avenger, so that the manslayer will not die until he stands trial before the assembly.

13 The cities you select will be your six cities of refuge.

Read all of Numbers 35