Numbers 35:8

And the cities which ye shall give shall be of the possession of the children of Israel, selected from the territory apportioned to the tribes; 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. As the plan worked out afterward, Joshua 21, there were ten cities of the Levites in the country east of the Jordan and thirty-eight in Canaan proper. By living in the midst of all the tribes, the Levites were to be an example to the entire nation, continually reminding them of their divine call and of the covenant of Jehovah, so that the fear of the Lord might be maintained in Israel.