Deuteronomy 25:12

Thine eye shall not pity him, but thou shalt put away the guilt of innocent blood from Israel, that it may go well with thee.

And thine eye shall not pity; but life shall go for life, eye for eye, tooth for tooth, hand for hand, foot for foot.

And when the LORD thy God shall deliver them before thee; thou shalt smite them, and utterly destroy them; thou shalt make no covenant with them, nor shew mercy unto them: