'Enemy' in the Bible

Rejoice not when thine enemy falleth, and let not thine heart be glad when he stumbleth:

If thine enemy be hungry, give him bread to eat; and if he be thirsty, give him water to drink:

On his lips, an enemy will pretend, but {inside} he will harbor deceit.

Faithful are the wounds of a friend; but the kisses of an enemy are deceitful.

Whoever shares with a thief is his own enemy; he hears the oath to testify, but does not talk.