Give instruction to a wise man and he will become even wiser;
Teach a righteous man and he will increase his learning.
The [reverent] fear of the Lord [that is, worshiping Him and regarding Him as truly awesome] is the beginning and the preeminent part of wisdom [its starting point and its essence],
And the knowledge of the Holy One is understanding and spiritual insight.
For by me (wisdom from God) your days will be multiplied,
And years of life shall be increased. – Proverbs 9:9-11
James describes such wisdom as “first pure [morally and spiritually undefiled], then peace-loving [courteous, considerate], gentle, reasonable [and willing to listen], full of compassion and good fruits. It is unwavering, without [self-righteous] hypocrisy [and self-serving guile].” These elements produce a good life, a life of spiritual wisdom. All of them are opposites of evil, of causing harm. Godly fear causes a person to test properly and to arrive at the correct conclusion about what they should or should not do. Ultimately, the fear of the Lord teaches us to live eternally—to live with the skill that the Father and the Son have in living. – Forerunner Commentary
The knowledge of God the Father, who is holy in his nature and works; not a mere natural knowledge of him by the light of nature; nor a mere notional knowledge of him by revelation; not a legal knowledge of him as a lawgiver, and an offended Judge; but an evangelical knowledge of him in Christ, as his God and Father; and as the God of all grace in him; so as to have faith and hope in him, access unto him, and communion with him; this is right understanding: so the knowledge of Christ, God’s Holy One; a knowledge of him in his person, offices, and grace; an inward knowledge of him, a spiritual acquaintance with him, so as to approve of him, believe in him, and appropriate him to one’s self; this is to attain to a good degree of understanding: as likewise the knowledge of the Holy Spirit, the author of sanctification; of his person, and operations of grace; as a convincer and comforter; as a Spirit of illumination and faith, of regeneration and sanctification; and as the Spirit of adoption, and the earnest of glory; this is another branch of spiritual understanding. Moreover, such knowledge which holy men have, and which makes them so; and which holy men of God, moved by the Holy Ghost, have communicated in the sacred Scriptures, of which they are the penmen. The knowledge of holy things may also be meant; of the holy mysteries of religion, of the holy doctrines of the Gospel, which are all according to godliness, and teach men to live in a holy manner: the faith once delivered to the saints is a most holy faith, encourages and promotes holiness of heart and life; as the doctrines of God’s everlasting love; eternal election; the unconditionality of the covenant of grace; redemption by Christ; conversion by efficacious grace; justification by Christ’s righteousness; pardon by his blood; satisfaction by his sacrifice; and perseverance by his power: and now a knowledge of these things, not notional, but experimental, is understanding indeed; as well as a knowledge of holy and gracious experiences. – John Gill