Deuteronomy 19:8-10

CLV(i) 8 And when Yahweh your Elohim widens your territory just as He had sworn to your fathers, and gives to you the whole land that He had promised to give to your father. 9 (in case you observe all of this instruction to obey it, that I am enjoining on you today, to love Yahweh your Elohim and to walk in His ways all the days), then you must add for yourself three more cities to these three. 10 Thus within your land that Yahweh your Elohim is giving to you as an allotment, the blood of the innocent shall not be shed so that no guilt of bloodshed comes to be on you.