Job 12:12

With the ancient [is] wisdom
Meaning not himself, who was not very ancient; though some think Eliphaz so understood him; hence those words of his, in ( Job 15:9 Job 15:10 ) ; rather, as others, Job tacitly wishes that some ancient man, with whom wisdom was, would undertake to examine the affair between him and his friends, and judge of it, and decide the point; or, as others, he has respect to Bildad's advice to search the fathers, and learn their sentiments, and be determined by them; to which he replies, that though it will be allowed that wisdom is with them, for the most part, yet their judgment of things is no further to be regarded than as it agrees with the wisdom of God, and the revelation he has made of his will; though it seems best of all to consider these words as an adage or proverbial sentence generally agreed to, that it often is, as it might be expected it should, though it is not always, that men well advanced in years are wise; that as they have lived long in the world, they have learned much by observation and experience, and have attained to a considerable share of wisdom and knowledge in things, natural, civil, and religious:

and in length of days is understanding;
the understandings of men are improved and enriched, and well stored with useful science, having had the opportunity of much reading, hearing, and conversation; by this Job would suggest, that if his friends had more knowledge of hidden and recondite things, beyond common people, which yet they had not, it was not so wonderful, since they were aged men, and had lived long in the world; or rather it may be that this is mentioned, to observe that from hence, seeing it is so among men, that ancient men have, or it may be expected they should have, a considerable share of wisdom and understanding; it may be most easily and strongly concluded, that God, who is the Ancient of days, has the most perfect and consummate wisdom and knowledge, which is asserted in ( Job 12:13 ) .