A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
pro 26:1(Pro. 26:1-28)
The incongruities of nature illustrate also those of the moral world. The fool's unworthiness is also implied (Pro 17:7; Pro 19:10).
pro 26:2Though not obvious to us,
the bird--literally, "sparrow"--and
swallow--have an object in their motions, so penal evil falls on none without a reason.
pro 26:3The rod is as much needed by fools and as well suited to them, as whips and bridles are for beasts.
pro 26:4Answer not--that is, approvingly by like folly.
pro 26:5Answer--by reproof.
pro 26:6A fool fails by folly as surely as if he were maimed.
drinketh damage--that is, gets it abundantly (Job 15:16; Job 34:7).
pro 26:7legs . . . equal--or, "take away the legs," or "the legs . . . are weak." In any case the idea is that they are the occasion of an awkwardness, such as the fool shows in using a parable or proverb (see Introduction; Pro 17:7).
pro 26:8A stone, bound in a sling, is useless; so honor, conferred on a fool, is thrown away.
pro 26:9As vexatious and unmanageable as a thorn in a drunkard's hand is a parable to a fool. He will be as apt to misuse is as to use it rightly.
pro 26:10Various versions of this are proposed (compare Margin). Better perhaps--"Much He injures (or literally, "wounds") all who reward," &c., that is, society is injured by encouraging evil men.
transgressors--may be rendered "vagrants." The word "God" is improperly supplied.
pro 26:11returneth . . . folly--Though disgusting to others, the fool delights in his folly.
pro 26:12The self-conceited are taught with more difficulty than the stupid.
pro 26:13(Compare Pro 22:13).
pro 26:14(Compare Pro 6:10; Pro 24:33).
pro 26:15(Compare Pro 19:24).
pro 26:16The thoughtless being ignorant of their ignorance are conceited.
pro 26:17meddleth--as in Pro 20:19; Pro 24:21; as either holding a dog by the ears or letting him go involves danger, so success in another man's strife or failure involves a useless risk of reputation, does no good, and may do us harm.
pro 26:18Such are reckless of results.
pro 26:20The talebearers foster (Pro 16:28), and the contentious excite, strife.
pro 26:22(Compare Pro 18:8).
pro 26:23Warm professions can no more give value to insincerity than silver coating to rude earthenware.
pro 26:24dissembleth--though an unusual sense of the word (compare Margin), is allowable, and better suits the context, which sets forth hypocrisy.
pro 26:25Sentiment of Pro 26:24 carried out.
seven abominations in his heart--that is, very many (compare Pro 24:16).
pro 26:26Deceit will at last be exposed, and the wicked by their own arts often bring on retribution (compare Pro 12:13; Psa 7:16; Psa 9:17, &c.).
pro 26:28Men hate those they injure.
A lying tongue--"lips" for the persons (compare Pro 4:24; Psa 12:3).