Albert Barnes Commentary Proverbs 14:33

"Wisdom resteth in the heart of him that hath understanding; But [that which is] in the inward part of fools is made known." — Proverbs 14:33 (ASV)

Omit “that which is.” “Wisdom” is the subject of both clauses. She is “made known,” that is, by the very force of contrast, in the midst of fools; or she is reserved and reticent in the one, noisy and boastful in the other. The Septuagint and some other versions get over the difficulty, by reading “Wisdom is not made known.”