'Your Enemy' in the Bible

"You have heard that it was said, "You shall love your neighbor and hate your enemy."

On the contrary, therefore, If your enemy is hungry, feed him; if he is thirsty, give him drink; for by so doing you will be heaping burning coals on his head.

Am I then become your enemy, because I am telling you the truth?

Be temperate, be vigilant; because your enemy, the devil, is prowling about like a roaring lion, seeking whom he may devour.