The Levitical cities were in an special manner the Lord’s; and therefore the places of refuge, where the manslayer might remain under the protection of a special institution devised by divine mercy, were appropriately selected from among them. No doubt also the Priests and Levites would be the fittest persons to administer the law in the doubtful cases which would be sure to occur: compare Numbers 35:24 note.
Related Commentaries of Numbers 35:6
Numbers 35:6
6 And among the cities which ye shall give unto the Levites there shall be six cities for refuge, which ye shall appoint for the manslayer, that he may flee thither: and to them ye shall add forty and two cities.