Numbers 35:11-13

Amplified Bible

¹¹ then you shall select for yourselves cities to be cities of refuge, so that the one who kills any person unintentionally may escape there. ¹² The cities shall be to you as a refuge from the avenger, so that the one who has caused the death of another will not be killed until he has had a [fair] trial before the congregation. ¹³ The cities which you are to provide shall be your six cities of refuge.