He will surely reprove you, if ye do secretly accept persons - If you show partiality, you will incur his disapprobation. This seems to have much era proverbial cast, and to mean that under no possible circumstances was it right to show partiality. No matter for whom it may be done, it will be displeasing to God. Even if it be in favor of the righteous, the widow, the fatherless, or of himself, if there is not a disposition to judge according to truth and evidence, God will frown upon you. No matter who the parties might be; no matter what their rank; no matter what friendship there might be for one or the other of them, it was never to be assumed that one was right and the other wrong without evidence. The exact truth was to be sought after, and the judgement made up accordingly. Even when God was one of the parties, the same course was to be pursued. His character was capable of being successfully vindicated, and he would not be pleased to have his cause defended or decided by partiality, or by mere favor. Hence, he encourages people to bring forth their strong reasons, and to adduce all that can be said against his government and laws. See the notes at Isaiah. 41:1-21.

He will surely reprove you - You may expect, not only his disapprobation, but his hot displeasure.

He will surely reprove you,.... Or "in reproving he will reprove you" (r); he will certainly do it, it may be depended upon, and be expected; he will never suffer sin to go unreproved and uncorrected; he will do it to the purpose, with sharpness and severity, as the nature of the crime requires; he reproves by his spirit, and it is well for men when he thoroughly, and in a spiritual and saving way, reproves them by him, and convinces them of sin, righteousness, and judgment; and he reproves by his word, which is written for reproof and correction; and by his ministers, one part of whose work it is to rebuke and reprove men for bad practices, and bad principles; and in some cases they are to use sharpness, and which when submitted to, and kindly taken, it is well; and sometimes he reproves by his providences, by afflictive dispensations, and that either in love, as he rebukes his own children, or in wrath and hot displeasure, as others, which is here designed; and as it is always for sin he rebukes men, so particularly he rebukes for the following, as might be expected:
if ye do secretly accept persons; acceptance of persons in judgment is prohibited by God, and is highly resented by him; yea, even the acceptance of his own person to the prejudice of the character of an innocent man; which seems to be what Job has respect unto, as appears from Job 13:8; and some versions render it, "if ye accept his face" (a); and though this may be done no openly and publicly, but in a covert and secret manner, under disguise, and with specious pretences to the honour and glory of God.
(r) "arguiendo arguet", Pagninus, Montanus, Munster, Bolducius, Mercerus, Cocceius, Schmidt; "redarguendo redarguet", Michaelis. (a) "faciem ejus", V. L. Munster, Piscator; "personam ipsius", Beza, so the Targum.

If ye do, though secretly, act partially. (See on Job 13:8; Psalm 82:1-2). God can successfully vindicate His acts, and needs no fallacious argument of man.