'Enemy' in the Bible

Ye have heard that it has been said, Thou shalt love thy neighbour and hate thine enemy.

but while men slept, his enemy came and sowed darnel amongst the wheat, and went away.

And he said to them, A man that is an enemy has done this. And the bondmen said to him, Wilt thou then that we should go and gather it up?

and the enemy who has sowed it is the devil; and the harvest is the completion of the age, and the harvestmen are angels.