Genesis 9:6 - Whoever sheds the blood of man, by man shall his blood be shed.
Proverbs 21:15 - When justice is done, it brings joy to the righteous but terror to evildoers.
Deuteronomy 19:21 - Show no pity: life for life, eye for eye, tooth for tooth, hand for hand, foot for foot.
Romans 13:4 - But if you do wrong, be afraid, for he does not bear the sword for nothing. He is God's servant, an agent of wrath to bring punishment on the wrongdoer.
And my own personal favorite:
Hosea 8:7 - For they sow the wind, and they shall reap the whirlwind.