The wise in heart shall be called prudent. True wisdom is recognized and acknowledged as such, especially when it has the gift of expressing itself appropriately (see on Proverbs 24:8). The sweetness (Proverbs 27:9) of the lips increaseth learning.
People listen to instruction at the mouth of one who speaks well and winningly. Such a one augments knowledge in others, and in himself too, for he learns by teaching. Knowledge ought not to be buried in one's own mind, but produced on fit occasions and in suitable words for the edification of others.
Ec Proverbs 20:30, "Wisdom that is hid, and treasure that is hoarded up, what profit is in them both?" (see Matthew 5:15). Septuagint, "The wise and prudent they call worthless ( φαύλους); but they who are sweet in word shall hear more."
Wise men are called bad and worthless by the vulgar herd, either because they do not impart all they know, or because they are envied fear their learning; but those who are eloquent and gracious in speech shall receive much instruction from what they bear, every one being ready to converse with them anal impart any knowledge which they possess.