Charles Ellicott Commentary Proverbs 18:4

"The words of a man`s mouth are [as] deep waters; The wellspring of wisdom is [as] a flowing brook." — Proverbs 18:4 (ASV)

The words of a man’s mouth are as deep waters—that is, the words of a “man,” properly so called, are as deep waters which cannot be easily fathomed; they are a copious stream, which flows from a never-failing source; they are a fountain of wisdom which is never exhausted.