Matthew 5:43-48 New King James Version (NKJV)

43 “You have heard that it was said, ‘You shall love your neighbor[a] and hate your enemy.’ 44 But I say to you, love your enemies, bless those who curse you, do good to those who hate you, and pray for those who spitefully use you and persecute you,[b] 45 that you may be sons of your Father in heaven; for He makes His sun rise on the evil and on the good, and sends rain on the just and on the unjust. 46 For if you love those who love you, what reward have you? Do not even the tax collectors do the same? 47 And if you greet your brethren[c] only, what do you do more than others? Do not even the tax collectors[d] do so? 48 Therefore you shall be perfect, just as your Father in heaven is perfect.

Hating your enemies was a codicil stuck onto the Law by religious folks who wanted to help God along a bit by recognizing human nature.  God says I recognize human nature and that is why the Law will never be abrogated.  Every jot and tittle must be fulfilled.  One of the jots is loving and blessing our enemies with the perfection of the Father in heaven (Matt. 5: 43-48).