The King James Bible addresses loving one's enemies in several passages:
Matthew 5:43-45 (KJV)
43 Ye have heard that it hath been said, Thou shalt love thy neighbour, and hate thine enemy. 44 But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you; 45 That ye may be the children of your Father which is in heaven: for he maketh his sun to rise on the evil and on the good, and sendeth rain on the just and on the unjust.
Luke 6:27-28 (KJV)
27 But I say unto you which hear, Love your enemies, do good to them which hate you, 28 Bless them that curse you, and pray for them which despitefully use you.
Romans 12:19-21 (KJV)
19 Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord. 20 Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head. 21 Be not overcome of evil, but overcome evil with good.
Proverbs 25:21-22 (KJV)
21 If thine enemy be hungry, give him bread to eat; and if he be thirsty, give him water to drink: 22 For thou shalt heap coals of fire upon his head, and the LORD shall reward thee.
Exodus 23:4-5 (KJV)
4 If thou meet thine enemy’s ox or his ass going astray, thou shalt surely bring it back to him again. 5 If thou see the ass of him that hateth thee lying under his burden, and wouldest forbear to help him, thou shalt surely help with him.