Numbers 35:7
So all the cities which ye shall give to the Levites shall be forty and eight cities: them shall ye give with their suburbs. So all the cities which ye shall give to the Levites shall be forty and eight cities: them shall ye give with their suburbs.
In the allotment of Canaan Levi was not counted for a tribal territory and received no tribal inheritance as the other tribes did. The exception was made because the tribe was devoted to sanctuary service. Instead, forty-eight cities distributed in different parts of the country throughout the land were assigned to the Levites as their inheritance. Those cities were to be their permanent homes, and they were to be given together with their surrounding suburbs.