John Gill Commentary Job 31:5

"If I have walked with falsehood, And my foot hath hasted to deceit" — Job 31:5 (ASV)

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 has 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) .