Numbers 35:6

35:6 Now from these towns that you will give to the Levites you must select six towns of refuge to which a person who has killed someone may flee. And you must give them forty-two other towns.

Numbers 35:15

35:15 These six towns will be places of refuge for the Israelites, and for the foreigner, and for the settler among them, so that anyone who kills any person accidentally may flee there.

Numbers 35:27-28

35:27 and the avenger of blood finds him outside the borders of the town of refuge, and the avenger of blood kills the slayer, he will not be guilty of blood, 35:28 because the slayer should have stayed in his town of refuge until the death of the high priest. But after the death of the high priest, the slayer may return to the land of his possessions.

Numbers 35:32

35:32 And you must not accept a ransom for anyone who has fled to a town of refuge, to allow him to return home and live on his own land before the death of the high priest.