Numbers 35:8-12

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.

And the LORD spake unto Moses, saying,

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

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.

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.