Numbers 35:9

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

8And 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.

9And the LORD spake unto Moses, saying,

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

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