John Gill Commentary Proverbs 5:2

"That thou mayest preserve discretion, And that thy lips may keep knowledge." — Proverbs 5:2 (ASV)

That you may regard discretion
Observe it; retain it in your heart, as Aben Ezra adds, and use it; think, speak, and act discreetly, and so avoid the bad woman afterwards described: the Vulgate Latin version is, "that you may keep the thoughts"; and so Gersom interprets the word; "good thoughts", according to the Septuagint version; the thoughts of the heart are to be observed. A man of spiritual wisdom will take notice of them; evil thoughts, which lead to uncleanness, are to be repressed and kept in; good ones to be cherished and improved; wise and sagacious ones (such the word here used signifies) are to be attended to, as being of great advantage in the various affairs and business of life; and spiritual and evangelical wisdom helps to such thoughts, and directs to the observance and exercise of them.

and [that] your lips may keep knowledge ;
may be able to speak of things worthy to be known, and communicate the knowledge of them to others; by which means useful knowledge will be kept and preserved, and be continued in successive ages; see (Malachi 2:7) ; even the knowledge of God and of Christ, and of the Gospel and its doctrines; and which will be a means of preserving men, as from false doctrine, error, and heresy, so from profaneness and immorality; and particularly from the adulterous woman, next described.