Go from the presence of a foolish man. There is some doubt about the rendering of this passage. The Vulgate gives, vade contra stultum, which is probably to be taken in the sense of the Authorized Version.
The Revised Version has, "Go into the presence of a foolish man." The Hebrew מִנֶּגֶד (minneged) may mean "from before," "over against," "in the presence of." Hence arises an ambiguity. The Authorized Version considers the sentence to be an injunction to turn away from a stupid man when you perceive that you can do him no good.
The Revised Version is equivalent to "if you go into the presence," etc. When thou perceivest not in him the lips of knowledge; Revised Version, and thou shalt not perceive in him, etc; which embodies a truism with no special point.
The whole sentence is better translated, Go forth from the presence of a foolish man, and thou hast not known the lips of knowledge; i.e; as Nowack explains, "Leave the presence of a fool, and you carry nothing away with you; after all your intercourse with him, you quit his presence without having gained any advance in true knowledge" (see on Proverbs 20:15).
The LXX. presents a very different version: "All things are adverse to a foolish man; but wise lips are the arms of knowledge ( αἰσθήσεως)." A foolish man, by his inconsiderate, slanderous, or bitter words, makes every one his enemy; a wise man uses his knowledge to good purposes; his words are the instruments by which he shows what he is.