“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.” – Buddha, 568 – 488 B.C.E.
“The man who backbites an absent friend, nay, who does not stand up for him when another blames him, the man who angles for bursts of laughter and for the repute of a wit, who can invent what he never saw, who cannot keep a secret – that man is black at heart: mark and avoid him.” – Marcus Tullius Cicero, 104 – 43 B.C.E.