“The tongue may be an unruly member--
But silence poisons the soul.”

“But on her side the Colchian ceases not to foam with hellish poisons and to sprinkle all the silences of Lethe's bough: exerting her spells she constrains his reluctant eyes, exhausting all her Stygian power of hand and tongue.”
Contra Tartareis Colchis spumare venenis cunctaque Lethaei quassare silentia rami perstat et adverso luctantia lumina cantu obruit atque omnem linguaque manuque fatigat vim Stygiam.

Gaius Valerius Flaccus book Argonautica

“Silence is a deadly poison when you have no words.”

Anastacia (1968) American singer-songwriter

“Silence, maiden; thy tongue outruns thy discretion.”

Walter Scott book Ivanhoe

“Silence is worse; all truths that are kept silent become poisonous.”

Friedrich Nietzsche book Thus Spoke Zarathustra

“Hunger for vengeance poisoned the soul.”

Steven Erikson book Gardens of the Moon

“Even so the tongue is a little member, and boasteth great things. Behold, how great a matter a little fire kindleth! And the tongue is a fire, a world of iniquity: so is the tongue among our members, that it defileth the whole body, and setteth on fire the course of nature; and it is set on fire of hell.”

James, son of Zebedee major religious figure in Christian tradition and one of the Twelve Apostles

“BELLADONNA, n. In Italian a beautiful lady; in English a deadly poison. A striking example of the essential identity of the two tongues.”

Ambrose Bierce (1842–1914) American editorialist, journalist, short story writer, fabulist, and satirist

“Silence can ask all the questions, where the tongue is prone to ask only the wrong one.”

Robin Hobb book Fool's Errand

“Conversation in its true meaning isn't all wagging the tongue; sometimes it is a deeply shared silence.”

Robertson Davies book The Rebel Angels