Adam Clarke Bible Commentary
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.
Jamieson-Fausset-Brown Bible Commentary
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.
John Gill Bible Commentary
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.