Better to remain silent and be thought a fool than to speak and to remove all doubt
In the multitude of words there wanteth not sin: but he that refraineth his lips is wise.
(Proverbs 10:19)
He that hath knowledge spareth his words: and a man of understanding is of an excellent spirit. Even a fool, when he holdeth his peace, is counted wise: and he that shutteth his lips is esteemed a man of understanding.
(Proverbs 17:27-28)
A fool has no delight in understanding, but only in revealing his own opinion.
(Proverbs 18:2)
A fool's lips enter into contention, and his mouth calleth for strokes. A fool's mouth is his destruction, and his lips are the snare of his soul. The words of a talebearer are as wounds, and they go down into the innermost parts of the belly.
(Proverbs 18:6-8)
If a wise man contendeth with a foolish man, whether he rage or laugh, there is no rest.
(Proverbs 29:9)
A fool uttereth all his mind: but a wise man keepeth it in till afterwards.
(Proverbs 29:11)
Surely the serpent will bite without enchantment; and a babbler is no better. The words of a wise man's mouth are gracious; but the lips of a fool will swallow up himself. The beginning of the words of his mouth is foolishness: and the end of his talk is mischievous madness. A fool also is full of words: a man cannot tell what shall be; and what shall be after him, who can tell him?
(Ecclesiastes 10:11-14)