Numbers 35:10

7 So all the cities which ye shall give to the Levites shall be forty and eight cities: them shall ye give with their suburbs.

8 And the cities which ye shall give shall be of the possession of the children of Israel: from them that have many ye shall give many; but from them that have few ye shall give few: every one shall give of his cities unto the Levites according to his inheritance which he inheriteth.

9 And the LORD spake unto Moses, saying,

10 Speak unto the children of Israel, and say unto them, When ye be come over Jordan into the land of Canaan;

11 Then ye shall appoint you cities to be cities of refuge for you; that the slayer may flee thither, which killeth any person at unawares.

12 And they shall be unto you cities for refuge from the avenger; that the manslayer die not, until he stand before the congregation in judgment.

13 And of these cities which ye shall give six cities shall ye have for refuge.