Numbers 35:1-3

And Jehovah spake unto Moses in the plains of Moab by the Jordan at Jericho, saying, Command the children of Israel, that they give unto the Levites of the inheritance of their possession cities to dwell in; and suburbs for the cities round about them shall ye give unto the Levites. And the cities shall they have to dwell in; and their suburbs shall be for their cattle, and for their substance, and for all their beasts.