Adam Clarke on Job 26:4

Whose spirit came from thee? - Mr. Good renders the verse thus: From whom hast thou pillaged speeches? And whose spirit hath issued forth from thee? The retort is peculiarly severe; and refers immediately to the proverbial sayings which in several of the preceding answers have been adduced against the irritated sufferer; for which see Job 8:11-19; 15:20-35, some of which he has already complained of, as in Job 12:3, and following. I concur most fully therefore with Dr. Stock in regarding the remainder of this chapter as a sample, ironically exhibited by Job, of the harangues on the power and greatness of God which he supposes his friends to have taken out of the mouths of other men, to deck their speeches with borrowed lustre. Only, in descanting on the same subject, he shows how much he himself can go beyond them in eloquence and sublimity.

Job intimates that, whatever spirit they had, it was not the Spirit of God, because in their answers falsehood was found.