Deuteronomy 21:9

9 And [so] you shall purge the innocent blood from your midst, because you must do the right thing in the eyes of Yahweh.

Deuteronomy 21:9 Meaning and Commentary

Deuteronomy 21:9

So shalt thou put away the guilt of innocent blood from among
you
Which otherwise, the person not being found out, and brought to just punishment for it, would devolve upon the whole. Aben Ezra interprets it the punishment of innocent blood, which, by the above method being taken, would not be inflicted on them:

when thou shalt do that which is right in the sight of the Lord;
as it was to observe this law concerning the beheading of the heifer, with all the rites and ceremonies belonging to it here enjoined; as well as every other command, statute, and ordinance of the Lord, which are all right to be done, ( Psalms 19:8 ) .

Deuteronomy 21:9 In-Context

7 And they shall declare, and they shall say, 'Our hands did not shed this blood, and our eyes did not see [what was done].

8 Forgive your people, Israel, whom you redeemed, Yahweh, and [do] not {allow} the guilt of innocent blood in the midst of your people Israel, and let them be forgiven [with regard to] blood.'

9 And [so] you shall purge the innocent blood from your midst, because you must do the right thing in the eyes of Yahweh.

10 "When you go out for battle against your enemies, and Yahweh your God gives them into your hand, and you lead the captives away,

11 and you see among the captives a woman beautiful in appearance, and you become attached to her and you want to take her as [a] wife,