Teach us what we shall say unto him - This seems to be addressed to Job. It is the language of Elihu, implying that he was overawed with a sense of the majesty and glory of such a God. He knew not in what manner, or with what words to approach such a Being, and he asks Job to inform him, if he knew.
We cannot order our speech by reason of darkness - Job had repeatedly professed a desire to bring his cause directly before God, and to argue it in his presence. He felt assured that if he could do that, he should be able so to present it as to obtain a decision in his favor; see Job 13:3, note; Job 13:18-22, notes. Elihu now designs, indirectly, to censure that confidence. He says that he and his friends were so overawed by the majesty of God, and felt themselves so ignorant and so ill qualified to judge of him and his works, that they would not know what to say. They were in darkness. They could not understand even the works of his hands which were directly before them, and the most common operations of nature were inscrutable to them. How then could they presume to arraign God? How could they manage a cause before him with any hope of success? It is scarcely necessary to say, that the state of mind referred to here by Elihu is that which should be cultivated, and that the feelings which he expresses are those with which we should approach the Creator. We need someone to teach us. We are surrounded by mysteries which we cannot comprehend, and we should, therefore, approach our Maker with profound reverence and submission

Teach us what we shall say unto him? - Thou pretendest to be so very wise, and to know every thing about God, pray make us as wise as thyself, that we may be able to approach with thy boldness the Sovereign of the world; and maintain our cause with thy confidence before him. As for our parts, we are ignorant; and, on all these subjects, are enveloped with darkness. Mr. Good translates: -
"Teach us how we may address him,
When arrayed in robes of darkness."
It is a strong and biting irony, however we take it.

Teach us what we shall say unto him; [for] we cannot order [our speech] by reason of (p) darkness.
(p) That is, our ignorance: signifying that Job was so presumptuous, that he would control the works of God.

Teach us what we shall say unto him,.... To this wonder working God, of whose common works of nature we know so little; how we should reason with him about his works of Providence, when we know so little of these:
for we cannot order our speech by reason of darkness; by reason of darkness in themselves, which is in all men naturally, and even in the saints in this state of imperfection; and by reason of the clouds and darkness which are about the Lord himself, who is incomprehensible in his nature and perfections; and by reason of the darkness cast about his providential dealings with men, so that they are unsearchable and past finding out; and the best of men are at a loss how to order their speech, or discourse with God concerning these things.

Men cannot explain God's wonders; we ought, therefore, to be dumb and not contend with God. If Job thinks we ought, "let him teach us, what we shall say."
order--frame.
darkness--of mind; ignorance. "The eyes are bewilderingly blinded, when turned in bold controversy with God towards the sunny heavens" (Job 37:18) [UMBREIT].

Teach us - If thou canst. Say unto him - Of these things. Order - To maintain discourse with him, both because of the darkness of the matter, God's counsels being a great depth; and because of the darkness of our minds.