Romans 13:3 – 4
New International Version (NIV)
3 For rulers hold no terror for those who do right, but for those who do wrong. Do you want to be free from fear of the one in authority? Then do what is right and you will be commended. 4 For the one in authority is God's servant for your good. But if you do wrong, be afraid, for rulers do not bear the sword for no reason. They are God's servants, agents of wrath to bring punishment on the wrongdoer.
From BibleGateway.com: http://www.biblegateway.com/passage/?search=romans+13.3-4&version=NIV
NIV®