If I have walked with vanity - This is the second specification in regard to his private deportment. He says that his life had been sincere, upright, honest. The word vanity here is equivalent to falsehood, for so the parallelism demands, and so the word (שׁוא shâv') is often used; Psalm 12:3; Psalm 41:7; Exodus 23:1; Deuteronomy 5:20; compare Isaiah, Deuteronomy 1:13. The meaning of Job here is, that he had been true and honest. In his dealings with others he had not defrauded them; he had not misrepresented things; he had spoken the exact truth, and had done that which was without deception or guile.
If my foot hath hasted to deceit - That is, if I have gone to execute a purpose of deceit or fraud. He had never, on seeing an opportunity where others might be defrauded, hastened to embrace it. The Septuagint renders this verse, "If I have walked with scoffers - μετα γελοιαστῶν meta geloiastōn - and if my foot has hastened to deceit."

If I have walked with vanity - If I have been guilty of idolatry, or the worshipping of a false god: for thus שאו shau, which we here translate vanity, is used Jeremiah 18:15; (compare with Psalm 31:6; Hosea 12:11; and Jonah 2:9), and it seems evident that the whole of Job's discourse here is a vindication of himself from all idolatrous dispositions and practices.

If I have walked with vanity,.... Or with vain men, as Bar Tzemach interprets it, keeping company and having fellowship with them in their vain and sinful practices; or in the vanity of his mind, indulging himself in impurity of heart and life; or rather using deceitful methods to cheat and defraud others; for this seems to be another vice Job clears himself of, acting unjustly in his dealings with men, or dealing falsely with them:
or if my foot hath hasted to deceit; to cheat men in buying and selling, being ready and swift to do it, and in haste to become rich, which puts men oftentimes on evil ways and methods to attain it; see Proverbs 28:20.

Job's abstinence from evil deeds.
vanity--that is, falsehood (Psalm 12:2).

5 If I had intercourse with falsehood,
And my foot hastened after deceit:
6 Let Him weigh me in the balances of justice,
And let Eloah know my innocence.
7 If my steps turned aside from the way,
And my heart followed mine eyes,
And any spot hath cleaved to my hands:
8 May I sow and another eat,
And let my shoots be rooted out.
We have translated שׁוא (on the form vid., on Job 15:31, and the idea on Job 11:11) falsehood, for it signifies desolateness and hollowness under a concealing mask, therefore the contradiction between what is without and within, lying and deceit, parall. מרמה, deceit, delusion, imposition. The phrase הלך עם־שׁוא is based on the personification of deceit, or on thinking of it in connection with the מתי־שׁוא (Job 11:11). The form ותּחשׁ cannot be derived from חוּשׁ, from which it ought to be ותּחשׁ, like ויּסר Judges 4:18 and freq., ויּשׂר (serravit) 1-Chronicles 20:3, ויּעט (increpavit) 1-Samuel 25:14. Many grammarians (Ges. 72, rem. 9; Olsh. 257, g) explain the Pathach instead of Kametz as arising from the virtual doubling of the guttural (Dagesh forte implicitum), for which, however, no ground exists here; Ewald (232, b) explains it by "the hastening of the tone towards the beginning," which explains nothing, since the retreat of the tone has not this effect anywhere else. We must content ourselves with the supposition that ותּחשׁ is formed from a חשׁה having a similar meaning to חוּשׁ (חישׁ), as also ויּעט, 1-Samuel 15:19, comp. 1-Samuel 14:32, is from a עטח of similar signification with עיט. The hypothetical antecedent, Job 31:5, is followed by the conclusion, Job 31:6 : If he have done this, may God not spare him. He has, however, not done it; and if God puts him to an impartial trial, He will learn his תּמּה, integritas, purity of character. The "balance of justice" is the balance of the final judgment, which the Arabs call Arab. mı̂zân 'l-a‛mâl, "the balance of actions (works)."
(Note: The manual of ethics by Ghazzli is entitled mı̂zân el-a‛mâl in the original, מאזני צדק in Bar-Chisdai's translation, vid., Gosche on Ghazzli's life and works, S. 261 of the volume of the Berliner Akademie d. Wissensch. for 1858.)
Job 31:7 also begins hypothetically: if my steps (אשּׁוּרי from אשּׁוּר, which is used alternately with אשׁוּר without distinction, contrary to Ew. 260, b) swerve (תּטּה, the predicate to the plur. which follows, designating a thing, according to Ges. 146, 3) from the way (i.e., the one right way), and my heart went after my eyes, i.e., if it followed the drawing of the lust of the eye, viz., to obtain by deceit or extortion the property of another, and if a spot (מאוּם, macula, as Daniel 1:4, = מוּם, Job 11:15; according to Ew., equivalent to מחוּם, what is blackened and blackens, then a blemish, and according to Olsh., in מאוּמה...לא, like the French ne point) clave to my hands: I will sow, and let another eat, and let my shoots be rooted out. The poet uses צאצאים elsewhere of offspring of the body or posterity, Job 5:25; Job 21:8; Job 27:14; here, however, as in Isaiah, with whom he has this word in common, Job 34:2; Job 42:5, the produce of the ground is meant. Job 31:8 is, according to John 4:37, a λόγος, a proverb. In so far as he may have acted thus, Job calls down upon himself the curse of Deut. 38:20f.: what he sows, let strangers reap and eat; and even when that which is sown does not fall into the hands of strangers, let it be uprooted.

Walked - Dealt with men. Vanity - With lying, or falsehood. Deceit - If when I had an opportunity of enriching myself, by wronging others, I have readily and greedily complied with It.