Six of the cities you give the Levites are to be appointed as cities of refuge, to which a manslayer may flee. In addition to these, give the Levites forty-two other cities.

Numbers 35:5
You are also to measure two thousand cubits outside the city on the east, two thousand on the south, two thousand on the west, and two thousand on the north, with the city in the center. These areas will serve as larger pasturelands for the cities.

Deuteronomy 4:41
Then Moses set aside three cities across the Jordan to the east

Joshua 20:2
"Tell the Israelites to designate the cities of refuge, as I instructed you through Moses,

Joshua 20:7
So they set apart Kedesh in Galilee in the hill country of Naphtali, Shechem in the hill country of Ephraim, and Kiriath-arba (that is, Hebron) in the hill country of Judah.

And among the cities which you shall give to the Levites there shall be six cities for refuge, which you shall appoint for the manslayer, that he may flee thither: and to them you shall add forty and two cities.