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 28:1(Pro. 28:1-28)
A bad conscience makes men timid; the righteous are alone truly bold (Pro 14:26; Psa 27:1).
pro 28:2Anarchy producing contending rulers shortens the reign of each.
but by a man . . . prolonged--or, "by a man of understanding--that is, a good ruler--he who knows or regards the right, that is, a good citizen, shall prolong (his days)." Good rulers are a blessing to the people. Bad government as a punishment for evil is contrasted with good as blessing to the good.
pro 28:3A poor man, &c.--Such, in power, exact more severely, and so leave subjects bare.
pro 28:4They that forsake . . . wicked--Wrongdoers encourage one another.
pro 28:5(Compare Joh 7:17). Ignorance of moral truth is due to unwillingness to know it.
pro 28:6(Compare Pro 10:6). Riches cannot compensate for sin, nor the want of them affect integrity.
pro 28:7(Compare Pro 17:25).
riotous men--or, "gluttons" (Pro 23:20-21).
pro 28:8usury . . . unjust gain--(Compare Margin). The two terms, meaning nearly the same, may denote excessive interest. God's providence directs the proper use of wealth.
pro 28:9(Compare Pro 15:8; Pro 21:27).
hearing--that is, obeying. God requires sincere worshippers (Psa 66:18; Joh 4:24).
pro 28:10(Compare Pro 26:27).
pro 28:11A poor but wise man can discover (and expose) the rich and self-conceited.
pro 28:12great glory--or, cause for it to a people, for the righteous rejoice in good, and righteousness exalts a nation (Pro 14:34).
a man . . . hidden--that is, the good retire, or all kinds try to escape a wicked rule.
pro 28:13(Compare Psa 32:3-5). Concealment of sin delivers none from God's wrath, but He shows mercy to the humble penitent (Psa 51:4).
pro 28:14feareth--that is, God, and so repents.
hardeneth his heart--makes himself insensible to sin, and so will not repent (Pro 14:16; Pro 29:1).
pro 28:15The rapacity and cruelty of such beasts well represent some wicked men (compare Psa 7:2; Psa 17:12).
pro 28:16The prince . . . understanding--that is, He does not perceive that oppression jeopards his success. Covetousness often produces oppression, hence the contrast.
pro 28:17doeth violence . . . blood, &c.--or, that is oppressed by the blood of life (Gen 9:6), which he has taken.
to the pit--the grave or destruction (Pro 1:12; Job 33:18-24; Psa 143:7).
stay him--sustain or deliver him.
pro 28:18(Compare Pro 10:9; Pro 17:20). Double dealing is eventually fatal.
pro 28:19(Compare Pro 10:4; Pro 20:4).
vain persons--idle, useless drones, implying that they are also wicked (Pro 12:11; Psa 26:4).
pro 28:20maketh haste . . . rich--implying deceit or fraud (Pro 20:21), and so opposed to "faithful" or reliable.
pro 28:21respect of persons-- (Pro 24:23). Such are led to evil by the slightest motive.
pro 28:22(Compare Pro 28:20).
evil eye--in the general sense of Pro 23:6, here more specific for covetousness (compare Pro 22:9; Mat 20:15).
poverty . . . him--by God's providence.
pro 28:23(Compare Pro 9:8-9; Pro 27:5). Those benefited by reproof will love their monitors.
pro 28:24(Compare Mat 15:4-6). Such, though heirs, are virtually thieves, to be ranked with highwaymen.
pro 28:25of a proud heart--literally, "puffed up of soul"--that is, self-confident, and hence overbearing and litigious.
made fat--or, "prosperous" (Pro 11:25; Pro 16:20).
pro 28:26(Compare Pro 3:6-8).
walketh wisely--that is, trusting in God (Pro 22:17-19).
pro 28:27(Compare Pro 11:24-26).
hideth his eyes--as the face (Psa 27:9; Psa 69:17), denotes inattention.
pro 28:28The elevation of the wicked to power drives men to seek refuge from tyranny (compare Pro 28:12; Pro 11:10; Psa 12:8).