They become insolent, and wickedly talk of extortion. Some take the verb ymyqv, yamicu, in an active transitive sense, and explain it as meaning, that the wicked soften, that is to say, render others pusillanimous, or frighten and intimidate them. [1] But as the idiom of the language admits also of its being understood in the neuter sense, I have adopted the interpretation which agreed best with the scope of the passage, namely, that the wicked, forgetting themselves to be men, and by their unbounded audacity trampling under foot all shame and honesty, dissemble not their wickedness, but, on the contrary, loudly boast of their extortion. And, indeed, we see that wicked men, after having for some time got every thing to prosper according to their desires, cast off all sham and are at no pains to conceal themselves when about to commit iniquity, but loudly proclaim their own turpitude. "What!" they will say, "is it not in my power to deprive you of all that you possess, and even to cut your throat?" Robbers, it is true, can do the same thing; but then they hide themselves for fear. These giants, or rather inhuman monsters, of whom David speaks, on the contrary not only imagine that they are exempted from subjection to any law, but, unmindful of their own weakness, foam furiously, as if there were no distinction between good and evil, between right and wrong. If, however, the other interpretation should be preferred, That the wicked intimidate the simple and peaceable by boasting of the great oppressions and outrages which they can perpetrate upon them, I do not object to it. When the poor and the afflicted find themselves at the mercy of these wicked men, they cannot but tremble, and, so to speak, melt and dissolve upon seeing them in possession of so much power. With respect to the expression, They speak from on high, [2] implies, that they pour forth their insolent and abusive speech upon the heads of all others. As proud men, who disdain to look directly at any body, are said, in the Latin tongue, despicere, and in the Greek, Katablepein, that is, to look down; [3] so David introduces them as speaking from on high, because it seems to them that they have nothing in common with other men, but think themselves a distinct class of beings, and, as it were, little gods.

Footnotes

1 - "Exposans que les meschans amolissent, c'est a dire, rendent lasches les autres, c'est a dire, les espouantent et intimident." -- Fr ymyqv, yamicu, is rendered by Vatablus, Cocceius, Gejer, and Michaelis, "They cause to consume or melt away." "They melt or dissolve others," says Dr Gill, "they consume them, and waste their estates by their oppression and violence; they make their hearts to melt with their threatening and terrifying words; or they make them dissolute in their lives by keeping them company." Mudge reads, "They behave corruptly;" and Horsley, "They are in the last stage of degeneracy."

2 - The original word, mmrvm, memmarom, for from on high, is translated by our English version loftily But Musculus, Junius, Tremellius, Piscator, Mudge, Horsley, and others read with Calvin, from on high They speak from on high, "as if they were in heaven and above all creatures, and even God himself; and as if what they said were oracles, and to be received as such without any scruple and hesitation. Thus Pharaoh, Sennacherib, and Nebuchadnezzar spake, Exodus 5:2; Isaiah 36:20; Daniel 3:15." -- Dr Gill

3 - "Car comme les Latins et aussi les Grecs, quand ils descrivent la contenance des gens enyvrez d'orgueil, ont des verbes qui signifient Regarder en bas, d'autant que telles gens ne daignent pas regarder droit les personnes." -- Fr. "As the Romans, and also the Greeks, when they describe the countenance of persons intoxicated with pride, have words which mean to look down, because such persons deign not to look directly at other people."

They are corrupt - literally, "they mock." The word rendered "they are corrupt" never has this signification. It is the very word - מוק mûq - from which our word mock is derived, and means the same thing. The idea is that they deride religion, or mock at all that pertains to God, and to the retributions of the future world.
And speak wickedly concerning oppression - literally, "they speak in wickedness; oppression they speak from on high." That is, they use arrogant language; they speak in a proud manner, as if they were above others; they use harsh and violent language, not regarding the feelings or the rights of others.

They are corrupt - ימיקו yamiku, they mock, act dissolutely.
And speak wickedly concerning oppression - They vindicate excessive acts of government: they push justice to its rigour. They neither show equity, lenity, nor mercy; they are cruel, and they vindicate their proceedings.

They are corrupt,.... In themselves, in their principles, and in their practices, being shapen and conceived in sin, and born of the flesh; and are corrupters, or "corrupt" themselves, and their ways, and also others by their corrupt speech, evil communications, and bad examples: or "they consume away"; like smoke, or into it, as Psalm 37:20 or as wax melteth at the fire, Psalm 68:2, where the same word is used as here: or "they cause to consume away" (o); "they melt or dissolve others"; they consume them, and waste their estates by their oppression and violence; they make their hearts to melt with their threatening and terrifying words; or they make them dissolute in their lives by keeping them company:
and speak wickedly concerning oppression; they speak oppression and revolt, threaten with it, Isaiah 59:13, and speak in vindication of it, and in a boasting glorying manner; so Arama; which is speaking wickedly concerning it:
they speak loftily: proudly, arrogantly, in a haughty and imperious manner: or "from on high" (p); as if they were in heaven, and above all creatures, and even God himself; and as if what they said were oracles, and to be received as such, without any scruple and hesitation. Thus Pharaoh, Sennacherib, and Nebuchadnezzar spake, Exodus 5:2 and the little horn, or antichrist, Daniel 7:20.
(o) "dissolutos reddunt", Vatablus; "reddent se dissolutos", Montanus; "faciunt tabescere", Cocceius, Gejerus, Michaelis. (p) "a sublimi", Musculus, Tigurine version, Junius & Tremellius, Piscator; "ex alto", Cocceius, Gejerus, Michaelis.

They are corrupt--or, literally, "they deride," they speak maliciously and arrogantly and invade even heaven with blasphemy (Revelation 13:6), and cover earth with slanders (Job 21:7-14).

And speak - Boasting of their oppressions.