A new proverb has been posted to the Mishlei section as of today (Monday June 8).
The lips of the wise spread [true] knowledge, but not so the heart of fools.
This proverb compares the idea development process among wise men with that among fools. The lips are the end point of the process, but for wise men it matches the origin, which is the heart. Thus, the knowledge that is passed by their lips is true. But that is not the case for fools, who have distorted the knowledge produced in their hearts before it reaches their lips.