Matthew 5:43-48 (New International Version)
Love for Enemies
43"You have heard that it was said, 'Love your neighbor and hate your enemy.' 44 But I tell you: Love your enemies and pray for those who persecute you, 45 that you may be sons of your Father in heaven. He causes his sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous. 46 If you love those who love you, what reward will you get? Are not even the tax collectors doing that? 47 And if you greet only your brothers, what are you doing more than others? Do not even pagans do that? 48 Be perfect, therefore, as your heavenly Father is perfect.
Pretty much all I have to say about that