Who is this - Referring doubtless to Job, for he is specified in the previous verse. Some have understood it of Elihu (see Schultens), but the connection evidently demands that it should be understood as referring to Job. The object was, to reprove him for the presumptuous manner in which he had spoken of God and of his government. It was important before God manifested his approval of Job, that he should declare his sense of what he had said, and show him how improper it was to indulge in language such as he had used.
That darkeneth counsel - That makes the subject darker. Instead of explaining the reason of the divine dealings, and vindicating God from the objections alleged against him and his government, the only tendency of what he had said had been to make his government appear dark, and severe, and unjust in the view of his friends. It might have been expected of Job, being a friend of God, that all that he said would have tended to inspire confidence in him, and to explain and vindicate the divine dealings; but, God had seen much that was the very reverse. Even the true friends of God, in the dark times of trial, may say much that will tend to make people doubt the wisdom and goodness of his government, and to prejudice the minds of the wicked against him.
By words without knowledge - Words that did not contain a true explanation of the difficulty. They conveyed no light about his dealings; they did not tend to satisfy the mind, or to make the subject more clear than it was before. There is much of this kind of speaking in the world; much that is written, and much that fails from the lips in debate, in preaching, and in conversation, that explains nothing, and that even leaves the subject more perplexed than it was before. We see from this verse that God does not and cannot approve of such "words." If his friends speak, they should vindicate his government; they should at least express their conviction that he is right; they should aim to explain his doings, and to show to the world that they are reasonable. If they cannot do this, they should adore in silence. The Savior never spoke of God in such a way as to leave any doubt that his ways could be vindicated, never so as to leave the impression that he was harsh or severe in his administration, or so as to lend the least countenance to a spirit of murmuring and complaining.

Who is this that darkeneth counsel - As if he had said, Who art thou who pretendest to speak on the deep things of God, and the administration of his justice and providence, which thou canst not comprehend; and leavest my counsels and designs the darker for thy explanation?

Who [is] this that (b) darkeneth counsel by words without knowledge?
(b) Which by seeking out the secret counsel of God by man's reason, makes it more obscure, and shows his own folly.

Who is this,.... Meaning not Elihu the last speaker, as some think; and there are some who suppose not only that these words are directed to him, but all that is said in this and the following chapter: but it was Job the Lord spoke to and answered, as expressed in Job 38:1; and these words are taken by Job to himself, Job 42:3. Concerning whom the Lord inquires, not as ignorant of him, who he was; but wondering that such a man as he should talk as he did; and as angry with him, and rebuking him for it;
that darkeneth counsel by words without knowledge? either his own counsel, his sense and sentiments of things, which were delivered in such an obscure manner as not to be intelligible by those that heard them; whereby they were led, as Job's friends were, into some mistaken notions of him: or rather the counsel of God, his works of providence, which are done according to the counsel of his will, and were misrepresented by Job, as not being wise and good, just and equitable; see Job 34:3.

this--Job.
counsel--impugning My divine wisdom in the providential arrangements of the universe. Such "words" (including those of the friends) rather obscure, than throw light on My ways. God is about to be Job's Vindicator, but must first bring him to a right state of mind for receiving relief.

Counsel - God's counsel. For the great matter of the dispute between Job and his friends, was concerning God's counsel and providence in afflicting Job; which Job had endeavoured to obscure and misrepresent. This first word which God spoke, struck Job to the heart. This he repeats and echoes to, Job 42:3, as the arrow that stuck fast in him.