I know [it is] so of a truth
That is, that God is just, and does not pervert justice and judgment, as Bildad had observed, ( Job 8:3 ) ; Job was a man of great natural parts and capacity; he had a large share of knowledge of things, natural, civil, and moral; and he was a good man, in whom the true light of grace shined; and being, enlightened by the spirit of wisdom and revelation, in the knowledge of divine things, he knew much of God, of his being and perfections, and of the methods of his grace, especially in the justification of men, as appears by various passages in this chapter; he knew that God was just and holy in all his ways and works, whether of providence or grace; and this he kept in sight amidst all his afflictions, and was ready to acknowledge it: he knew this "of a truth"; that is, most certainly; for there are some truths that are so plain and evident that a man may be assured of, and this was such an one with Job; he had no need to be instructed in this article; he was as knowing in this point, as well as in others, as Bildad or any of his friends; nor did he need to be sent to the ancients to inquire of them, or to prepare himself for the search of the fathers, in order to acquire the knowledge of this, to which Bildad had advised; yet, though this was so clear a point, about which there was no room for further contest; but then the matter is,
how should man be just with God?
if not angels, if not man in his best estate, in which he was vanity when compared with God; then much less frail, feeble, mortal, sinful men, even the best of men, considered in themselves, and with respect to their own righteousness: for, to "be just" is not to be so through an infusion of righteousness and holiness into men, which in the best of men is their sanctification and not their justification; but this is a legal term, and stands opposed to condemnation, and signifies a man's being condemned and pronounced righteous in a judiciary way; so a man cannot be adjudged, reckoned, or accounted by God upon the foot of works of righteousness done by him; since his best works are imperfect, not answerable to the law, but very defective, and so not justifying; are opposite to the grace of God, by which, in an evangelic sense, men are justified; these would encourage boasting, which is excluded in God's way of justifying sinners; and could justification be by them, the death of Christ would be in vain, and there would have been no need of him and his justifying righteousness: especially, it is a certain thing, that a man can never be "just", or "justified with God", in such a way, or through any righteousness wrought out by him; that is, either he is not and cannot be just in comparison of God; for, if the inhabitants of the heavens are not pure in his sight, the holy angels; and if man, at his best estate, was altogether vanity when compared with him, what must sinful mortals be? or not be just at his bar; should he mark their iniquities, enter into judgment with them, or an action against them, summon them before him to answer to charges he has to exhibit; they could not stand before him, or go off acquitted or discharged: or in his account; for his judgment is according to truth; he can never reckon that a perfect righteousness which is an imperfect one: or in his sight; for, though men may be just in comparison of others, or at an human bar, in an human court of judicature, and in the account of men, and in their sight, to whom they may appear outwardly righteous, as well as in their own sight; yet not in the sight of God, who sees all things, the heart and all in it, every action, and the spring of it; see ( Psalms 143:2 ) ( Romans 3:20 ) ; in this sense, a man can only be just with God through the imputation of the righteousness of Christ, accounting that to him, putting it upon him, and clothing him with it, and so reckoning and pronouncing him righteous through it; and which is entirely consistent with the justice of God, since by it the law is fulfilled, magnified, and made honourable, and justice satisfied; so that God is just, while he is the justifier of him that believes in Jesus, ( Romans 3:26 ) .