Musonius Rufus on Slander
"It is shameful to speak ill of anyone at all." — Musonius Rufus put it blunt: «αἰσχρὸν λέγειν κακῶς ὁποιοῦν τινα»

Salvator Rosa — "Self-Portrait" (ca. 1647), public domain
Strong words from a Stoic teacher.
In Lectures, fragment 52 (as preserved by Stobaeus), Musonius Rufus preached: «αἰσχρὸν λέγειν κακῶς ὁποιοῦν τινα» — "It is shameful to speak ill of anyone at all." This wasn’t just etiquette. For Musonius, every word shapes the soul.
Why slander was forbidden.
The Stoics believed speech was a mirror of character. To slander, even enemies, corrupts the speaker and fans the flames inside. Musonius drilled his students to cure their own faults before pointing out another’s flaws. Gossip was poison — and he demanded a cure.
The Stoic drillmaster.
Musonius Rufus taught in Rome and in exile, sometimes banned but never silenced. He scolded, grilled, and sometimes offended his audience. His call to self-mastery was meant for anyone tempted to vent behind closed doors — which is everyone.
Musonius Rufus warned that every insult stains the speaker, not the target. Gossip was vice, not sport.