Even as I have seen - Eliphaz appeals to his own observation, that people who had led wicked lives were suddenly cut off. Instances of this kind he might doubtless have observed - as all may have done. But his inference was too broad when he concluded that all the wicked are punished in this manner. It is true that wicked people are thus cut off and perish; but it is not true that all the wicked are thus punished in this life, nor that any of the righteous are not visited with similar calamities. His reasoning was of a kind that is common in the world - that of drawing universal conclusions from premises that are too narrow to sustain them, or from too few carefully observed facts.
They that plow iniquity - This is evidently a proverbial expression; and the sense is, that as people sow they reap. If they sow wheat, they reap wheat; if barley, they reap barley; if tares, they reap tares. Thus, in Proverbs 22:8 :
"He that soweth iniquity shall reap also vanity."
So in Hosea 8:7 :
"For they have sown the wind,
And they shall reap the whirlwind:
It hath no stalk; the bud shall yield no meal
If so be it yield, strangers shall swallow it up"
Thus, in the Persian adage:
"He that planteth thorns shall not gather roses."
Dr. Good.
So Aeschylus:
Ἄτης ἄρουρα Θάνατον ἐκκαρπίζεται.
Atēs aroura thanaton ekkarpizetai.
The field of wrong brings forth death as its fruit.
The meaning of Eliphaz is, that people who form plans of wickedness must reap appropriate fruits. They cannot expect that an evil life will produce ultimate happiness.

They that plough iniquity - A proverbial form of speech drawn from nature. Whatever seed a man sows in the ground, he reaps the same kind; for every seed produces its like. Thus Solomon, Proverbs 22:8 : "He that soweth iniquity shall reap vanity." And St. Paul, Galatians 6:7, Galatians 6:8 : "Be not deceived, God is not mocked; for whatsoever a man soweth, that shall he also reap. For he that soweth to his flesh, shall of the flesh reap corruption; but he who soweth to the Spirit, shall of the Spirit reap life everlasting." And of the same nature is that other saying of the apostle, He that soweth sparingly, shall reap sparingly, 2-Corinthians 9:6. The same figure is employed by the Prophet Hosea Hosea 8:7 : They have sown the wind, and they shall reap the whirlwind; and Hosea 10:12, Hosea 10:13 : Sow to yourselves in righteousness; reap in mercy. Ye have ploughed wickedness; ye have reaped iniquity. The last sentence contains, not only the same image, but almost the same words as those used by Eliphaz. Our Lord expresses the same thing, in the following words: Matthew 7:16-18 : Do men gather grapes of thorns, or figs of thistles? Every good tree bringeth forth good fruit, but a corrupt tree bringeth forth evil fruit. So the Greeks: -
Ατης αρουρα θανατον εκκαρπιζεται.
Aesch. Ἑπτα επι Θηβαις, ver. 607.
"The field of iniquity produces the fruit of death."
Ὑβρις γαρ εξανθους εκαρπωσε σταχυν
Ατης, ὁθεν παγκλαυτον εξαμᾳ θερος.
IB. Περσαι, ver. 823.
"For oppression, when it springs,
Puts forth the blade of vengeance; and its fruit
Yields a ripe harvest of repentant wo."
- Potter.
The image is common every where because it is a universal law of nature.

Even as I have seen, they that (e) plow iniquity, and sow wickedness, reap the same.
(e) They who do evil cannot but receive evil.

Even as I have seen,.... Here he goes about to prove, by his own experience, the destruction of wicked men; and would intimate, that Job was such an one, because of the ruin he was fallen into:
they that plow iniquity, and sow wickedness, reap the same; figurative expressions, denoting that such who devise iniquity in their hearts, form and plan schemes of it in their minds, signified by "plowing iniquity", and who were studious and diligent to put into practice what they devised; who took a great deal of pains to commit sin, and were constant at it, expressed by "sowing wickedness": these sooner or later eat the fruit of their doings, are punished in proportion to their crimes, even in this life, as well as hereafter, see Hosea 8:7 Galatians 6:7; though a Jewish commentator (b) observes, that the thought of sin is designed by the first phrase; the endeavour to bring it into action by the second; and the finishing of the work, or the actual commission of the evil, by the third; the punishment thereof being what is expressed in Job 4:9; the Targum applies this to the generation of the flood.
(b) R. Simeon Bar Tzemach.

they that plough iniquity . . . reap the same-- (Proverbs 22:8; Hosea 8:7; Hosea 10:13; Galatians 6:7-8).

Even - As thou hast never seen any example of a righteous man cut off, so I have seen many of wicked men cut off for their wickedness. They - They that designedly work wickedness, first preparing themselves for it, and then continuing to execute it, as husbandmen first plow the ground, and then cast in the feed. Reap - The fruit of their iniquity, the just punishment of it.