James 3:13 (ESV) … “Who is wise and understanding among you? By his good conduct let him show his works in the meekness of wisdom.”
James moves now from words to wisdom. The two concepts are, of course, closely related. Even an unregenerate man can hold his tongue when it is in his interest to do so. We have all known foul-spoken men who have refrained from cursing and obscenity when they are in the presence of a high-principled employer whom they know will not tolerate use of bad language. Wisdom controlled their words. They knew well enough that if they spoke to their boss the way they spoke to others, they would lose their job.
So James points first to the mainstream of wise behavior. The KJV put it this way: “Who is a wise man and endued with knowledge among you? Let him show out of a good conversation his works with meekness of wisdom.” A wise man does not need to boast. The old-fashioned word conversation here refers to a lifestyle and everyday behavior. Endued with knowledge comes from a word that means to have skill and understanding. It also means to know something well. The word for “meekness” is one that James has already used—we must “receive with meekness the engrafted word” (1:21).
Jesus exemplified all of these characteristics even as a boy (Luke 2:40, 52). James was blind to the wonder of Christ’s life until he met the risen Lord after His resurrection. He had sat at table with incarnate Wisdom. He had walked to and from school with Him. He had heard His answers to all kinds of questions. A greater than Solomon resided in that home in Nazareth, worked at that carpenter’s bench, and took the scroll in the synagogue to read and expound the Scriptures.
James calls on the people in the church who professed to be wise to “show” it. The word is emphatic. Thinking back over the years in Nazareth and the years of the Lord’s public ministry, and dwelling on His teaching, especially as enshrined in the Sermon on the Mount, James could have confessed that no one had ever shown wisdom more clearly and wonderfully than did Jesus.
 Phillips, J. (2009). Exploring the Epistle of James: An Expository Commentary (Jas 3:13). Kregel Publications; WORDsearch Corp.