A wise man gets more use from his enemies than a fool from his friends.

[Al varón sabio más le aprovechan sus enemigos que al necio sus amigos.]

Baltasar Gracián y Morales (1601-1658) Spanish Jesuit priest, writer, philosopher

The Art of Worldly Wisdom [Oráculo Manual y Arte de Prudencia], § 84 (1647) [tr. Jacobs (1892)]
    (Source)

See also Aristophanes. (Source (Spanish)). Alternate translations:

The wise man draws more advantage from his Enemies, than the fool does from his Friends.
[Flesher ed. (1685)]

To a wise man, his enemies avail him more, than to a fool, his friends.
[tr. Fischer (1937)]

The wise person finds enemies more useful than the fool finds friends.
[tr. Maurer (1992)]