Numbers 35:13 (BSB)

The cities you select will be your six cities of refuge.

From Numbers 35. Also in the ESV.

Commentary on Numbers 35:13

• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Numbers 35:13: And of these cities which ye shall give,.... Of the forty eight cities they were to give to the Levites, Num 35:7, six cities shall ye have for refuge; which, I think, makes it clear, that not all the forty eight cities were for refuge, only six of them.
• Keil & Delitzsch (Lutheran), Biblical Commentary on the Old Testament on Numbers 35:12-15: Num 35:12-15 These towns were to serve for a refuge from the avenger of blood, that the manslayer might not die before he had taken his trial in the presence of the congregation. The number of cities was fixed at six, three on the other side of the Jordan, and three on this side in the land of Canaan, to which both the children of...