Proverbs 12:23

A sharp man keeps back his knowledge; but the heart of foolish men makes clear their foolish thoughts.

Proverbs 13:16

A sharp man does everything with knowledge, but a foolish man makes clear his foolish thoughts.

Proverbs 15:2

Knowledge is dropping from the tongue of the wise; but from the mouth of the foolish comes a stream of foolish words.

Proverbs 11:13

He who goes about talking of others makes secrets public, but the true-hearted man keeps things covered.

Proverbs 10:14

Knowledge is stored up by the wise, but the mouth of the foolish man is a destruction which is near.

Proverbs 10:19

Where there is much talk there will be no end to sin, but he who keeps his mouth shut does wisely.

Ecclesiastes 10:3

And when the foolish man is walking in the way, he has no sense and lets everyone see that he is foolish.

Ecclesiastes 10:12-14

The words of a wise man's mouth are sweet to all, but the lips of a foolish man are his destruction.

Treasury of Scripture Knowledge

Summary

A prudent man concealeth knowledge: but the heart of fools proclaimeth foolishness.

General references

Bible References

A prudent

Proverbs 10:19
Where there is much talk there will be no end to sin, but he who keeps his mouth shut does wisely.
Proverbs 11:13
He who goes about talking of others makes secrets public, but the true-hearted man keeps things covered.
Proverbs 13:16
A sharp man does everything with knowledge, but a foolish man makes clear his foolish thoughts.

But

Proverbs 15:2
Knowledge is dropping from the tongue of the wise; but from the mouth of the foolish comes a stream of foolish words.
Ecclesiastes 10:3
And when the foolish man is walking in the way, he has no sense and lets everyone see that he is foolish.

General references

Proverbs 14:33
Wisdom has her resting-place in the mind of the wise, but she is not seen among the foolish.
Proverbs 29:11
A foolish man lets out all his wrath, but a wise man keeps it back quietly.

Basic English, produced by Mr C. K. Ogden of the Orthological Institute - public domain