Nothing is as dangerous as an ignorant friend; a wise enemy is to be preferred.

A false friend is more dangerous than an open enemy

Rien n'est si dangereux qu'un ignorant ami; Mieux vaudrait un sage ennemi.

What greater wound is there than a false friend?

Misfortune tests the sincerity of friendship.

An insincere and evil friend is more to be feared than a wild beast; a wild beast may wound your body, but an evil friend will wound your mind.

A doubtful friend is worse than a certain enemy. Let a man be one thing or the other, and we then know how to meet him.

One fake friend can do more harm than 10 enemies... Be smart choosing your friends.

the harm that’s in the world now as often comes through folly as through malice.

One enemy can do more hurt than ten friends can do good.

The friendship of wise men
Is tasteless as water.
The friendship of fools
Is sweet as wine.
But the tastelessness of the wise
Brings true affection
And the savor of fools' company
Ends in hatred.

If it was not for the company of fools, a witty man would often be greatly at a loss.

The wise man through an excess of wisdom is made a fool.

A man friends are more capable of working him harm than strangers; and his greatest
danger lies in his own habits.