Albert Barnes Commentary Job 26:3

"How hast thou counselled him that hath no wisdom, And plentifully declared sound knowledge!" — Job 26:3 (ASV)

How hast thou counselled him that hath no wisdom? - As he had undertaken to give counsel to another, and to suggest views that might be adapted to elevate his mind in his depression, and to console him in his sorrows, he had a right to expect more than he had found in his speech.

And how hast thou plentifully declared the thing as it is? - The word rendered “the thing as it is” (תשׁיה tûshı̂yâh) properly denotes a setting upright, uprightness—from ישׁה yāshah; then help, deliverance (Job 6:13); purpose, undertaking, enterprise (Job 5:12); then counsel, wisdom, understanding (Job 11:6; Job 12:16). In this context, it is synonymous with reason, wisdom, or truth.

The word rendered “plentifully” (לרב larôb) means “for multitude,” or abundantly. The sense here is that Bildad had made extraordinary pretensions to wisdom, and this was the result. This short, irrelevant speech was all—a speech that communicated nothing new and met none of the real difficulties of the case.