I have heard the check of my reproach - I have heard your violent and severe language reproaching us. Probably he refers to what Job had said in the close of his speech Job 19:29, that they had occasion to dread the wrath of God, and that they might anticipate heavy judgments as the result of their opinions. Or it may be, as Schultens supposes, that he refers to what Job said in Job 19:2, and the rebuke that he had administered there. Or possibly, and still more probably, I think, he may refer to what Job had said in reply to the former speech of Zophar Job 12:2, where he tauntingly says that "they were the people, and that wisdom would die with them." The Hebrew literally is, "the correction of my shame" (כלמה מוּסר mûsâr kelı̂mmâh), "the correction of my shame." that is, the castigation or rebuke which tends to cover me with ignominy. The sense is, "you have accused me of that which is ignominious and shameful, and under the impetuous feelings caused by such a charge I cannot refrain from replying."
And the spirit of my understanding - Meaning, perhaps, "the emotion of his mind." The word "mind" or "soul" would better express the idea than the word "understanding;" and the word "spirit" here seems to be used in the sense of violent or agitating emotions - perhaps in allusion to the primary signification of the word (רוּח rûach), "mind."

I have heard the check of my reproach - Some suppose that Zophar quotes the words of Job, and that some words should be supplied to indicate this meaning; e.g., "I have heard (sayest thou) the check or charge of my reproach?" Or it may refer to what Job says of Zophar and his companions, Job 19:2, Job 19:3 : How long will ye vex may soul - these ten times have ye reproached me. Zophar therefore assumes his old ground, and retracts nothing of what he had said. Like many of his own complexion in the present day, he was determined to believe that his judgment was infallible, and that he could not err.

I have heard (a) the check of my reproach, and the spirit of my understanding causeth me to answer.
(a) He declares that two things moved him to speak: that is, because Job seemed to touch him, and because he thought he had knowledge sufficient to confute him.

I have heard the check of my reproach,.... He took it that Job had reproached him and his friends, by representing them as hardhearted men, and persecuting him wrongly in a violent manner; and he had observed the "check" or reproof given for it, by bidding them beware of the sword, and lest the punishment of it should be inflicted on them; and if that should not be the case, yet there was a righteous judgment they could not escape. Now Zophar heard this, but could not hear it with patience; be could not bear that he and his friends should be insulted, as he thought, in this manner; and therefore it was he was in such baste to return an answer; though some (d) think he here pretends to a divine oracle, like that which Eliphaz makes mention of in the beginning of this dispute, Job 4:12, &c. which he had from God, and from which he had heard the "correction of his reproach" (e), or a full confutation of the thing Job had reproached him with; and being thus divinely furnished, he thought it his duty to deliver it:
and the spirit of my understanding causeth me to answer; or his rational spirit, his natural understanding, furnished him at once with an answer; he had such a clear insight into the controversy on foot, and such a full view of it, that he thought himself capable of speaking very particularly to the matter in hand, and to the conviction and confusion of Job; nay, his conscience, or the spirit of his conscience, as Mr. Broughton renders it, not only readily dictated to him what he should say, but obliged him to it; though some think he meant the Holy Spirit of God, by which he would be thought to be inspired; that he "out of his understanding" (f), enlightened by him, caused him to answer, or would answer for him, or supply him with matter sufficient to qualify him for it; and this he might observe to Job, in order to raise his attention to what he was about to say.
(d) Schmidt. (e) "correctionem ignominiae meae", Pagninus, Montanus; so Schmidt, Michaelis. (f) "ex intelligentia mea", Junius & Tremellius, Piscator, Mercerus, Drusius, Schmidt, Michaelis.

check of my reproach--that is, the castigation intended as a reproach (literally, "shame") to me.
spirit of . . . understanding--my rational spirit; answering to "calm thoughts" (Job 20:2). In spite of thy reproach urging me to "hastiness." I will answer in calm reason.

The check - Thy opprobrious reproofs of us. Understanding - I speak, not from passion, but certain knowledge.