There is a great risk in associating with people who have a distorted sense of right and wrong. Mishlei teaches that the prudent thing to do is to avoid such people whenever possible. Mishlei is especially concerned with the dangerous influence of a foolish person who is so conceited that he considers his own opinions as being irrefutably correct, even though you know them to be wrong. The danger from associating with such a person is so great that in ordinary circumstances, even if you only suspect him of having an immoral or unethical attitude, it is best to avoid him.
The foolish man in this context is actually an intelligent person who respects wisdom, but who has convinced himself that his distorted views are valid. Those distortions are motivated by what he perceives to be his self-interest. He is sufficiently conceited to confidently argue the rightness of his position and this makes him a dangerous adversary.
ז = לֵךְ מִנֶּגֶד לְאִישׁ כְּסִיל וּבַל יָדַעְתָּ שִׂפְתֵי דָעַת
(7) Get away from a foolish man,
even if you do not know him to have lips of knowledge.
This proverb emphasizes the importance of avoiding the company of a foolish man. The danger of associating with a fool is so great that you should avoid him even if the degree of his foolishness is unknown to you. You should only associate with someone you know to be wise, as evidenced by the way he speaks and what he says (“lips of knowledge”).
(7) Get away from a foolish man — לֵךְ מִנֶּגֶד לְאִישׁ כְּסִיל,
who considers his own foolish opinions as irrefutably correct.
And even avoid associating with him if you only suspect him
of a foolish attitude, that is, you do not know — וּבַל יָדַעְתָּ
him to have lips that speak knowledge — שִׂפְתֵי דָעַת,
(1) If you must have dealings with a fool, avoid any continuing long-term relationship with him and distance yourself from him as much as possible.
(רש”י, אבן עזרא, מצודות)
(2) Before committing yourself to a close association with anyone, find out about his personal qualities: Is he a man of his word? Does he respect a confidence? Does he refrain from insulting and embarrassing others? Is he subject to anger and conceit? (רבינו יונה)
(3) If you don’t distance yourself from the fool, you are in danger of being like him — “not knowing.” (מצודות)
(4) Use the excuse of “not knowing” whenever you are approached by a fool with a question or project that you want to avoid get involved with, or that you are uncertain about (Just say, “I don’t know!”). (המאירי, אלשיך)
(5) It is not foolish to admit ignorance, because if a person admits that he does not know, he will ultimately gain knowledge. (אלשיך)
(6) If you are uncertain about a person’s character, observe the way he speaks. See if he speaks with “lips of knowledge.” For example, if he is uncertain about what to say, he remains silent or says, “I don’t know.” (חנוך לנער)
(7) Many people have wisdom and knowledge, but are unable to convey and express it. Those who can’t – who don’t have “lips that speak knowledge” should be especially advised to stay away from fools. (דעת סופרים)
(8) What is the difference between the fool (כְּסִיל) and the scoffer (לֵץ) of the previous proverb? The fool respects wisdom but distorts it to please his selfish desires. The scoffer distorts it because he has no respect for anything. (מלבי”ם)