Albert Barnes Commentary Proverbs 10:13

"In the lips of him that hath discernment wisdom is found; But a rod is for the back of him that is void of understanding." — Proverbs 10:13 (ASV)

That is, the wisdom of the wise is seen in the words that come from his lips; the folly of the fool is not only seen in his speech but brings upon him the chastisement which he rightly deserves.