Deuteronomy 19:13

19:13 You must not pity him, but purge out the blood of the innocent from Israel, so that it may go well with you.

Deuteronomy 19:19

19:19 you must do to him what he had intended to do to the accused. In this way you will purge evil from among you.

Deuteronomy 21:9

21:9 In this manner you will purge out the guilt of innocent blood from among you, for you must do what is right before the Lord.