Numbers 15:28

15:28 And the priest must make atonement for the person who sins unintentionally – when he sins unintentionally before the Lord – to make atonement for him, and he will be forgiven.

Numbers 35:11

35:11 you must then designate some towns as towns of refuge for you, to which a person who has killed someone unintentionally may flee.

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.