Albert Barnes Commentary Job 33:3

"My words [shall utter] the uprightness of my heart; And that which my lips know they shall speak sincerely." — Job 33:3 (ASV)

My words shall be of the uprightness of my heart - I will speak in sincerity. I will utter nothing that will be hollow and hypocritical. What I speak will be the real suggestion of my heart - what I feel and know to be true.

Perhaps Elihu was the more anxious to make this point entirely clear because the three friends of Job might be thought to have exposed themselves to the suspicion that they were influenced by passion or prejudice; that they had maintained their opinions from mere obstinacy and not from conviction; and that they had sometimes been inclined to make petty objections. Elihu claims that all that he was about to say would be entirely sincere.

Shall utter knowledge clearly - He will state things just as they are and give the true solution of the difficulties that have been felt regarding the divine dealings. His object is to guard himself wholly from the suspicion of partiality.