The message of this proverb is straightforward and clear – “do not speak to fools.” Then, the reason for this command, “they will scorn your prudent words.”
At issue here is the situation of trying to talk rationally (“prudent words”) with a fool – by Biblical definition, one who does not include God in his worldview (Psa 14:1). It’s sort of like trying to talk sense with a drunk – we speak to each other, but on two different levels.
The result of such an exchange with a fool will be his lack of appreciation (“scorn”) for your words. The proverb suggests this will be a wasted effort.
Jesus actually discussed a similar situation when he said, “do not throw your pearls to pigs. If you do, they may trample them under their feet, and turn and tear you to pieces” (Mt 7:6). Pearls laying in the slop around a pig may well get trampled down into the mire, never to be seen again. Even worse, the pig might also turn around and go after me, too!
Prudent words and fools go together about as well as pearls and pigs. Neither’s a pretty picture!