This verse sits inside the father's lecture on adultery and the wife of your youth, Proverbs 5:1–23.
Quick answer
The purpose of the listening: discretion preserved, knowledge kept on the lips. The father wants his son equipped before the moment arrives, not lectured after.
Read the whole unit
This lecture is the book's most sustained treatment of sexual faithfulness, and it moves in three sweeps. First the warning (vv. 1–14): a woman who is not his speaks in honey and oil, and the father tracks where that road actually goes, past bitterness and a two-edged sword, past squandered vigor and years handed to strangers, ending in an old man's speech of regret spoken over a wasted body. Then the alternative (vv. 15–20), and this is what makes the chapter unusual: it does not finish with prohibition. It turns to water, cisterns, wells, and running streams, and tells the son to drink deeply at home, to rejoice in the wife of his youth, to be satisfied and delighted. The chapter's answer to a wrong love is a right one, offered warmly and without embarrassment. Finally the reason (vv. 21–23): the LORD is watching, weighing every path, and a man who refuses instruction is bound not by God's ropes but by his own.
Three words hold the lecture together, and each one repays attention.
The first is intoxication. The verb behind "enraptured" in verse 19 appears again in verse 20 and once more in verse 23, where it is rendered "go astray." The NKJV footnotes its literal sense at verse 19: intoxicated. So the lecture's spine is a single question about one capacity. The son is built to be swept away by love; the father never suggests otherwise and never asks him to want less. He asks him where the intoxication will be spent, because the same word that means delight in verse 19 means staggering in verse 23.
The second is weighing. Verse 21 says the LORD "ponders" every path, and the footnote gives the literal sense: weighs. It is the same verb the father used at 4:26, "Ponder the path of your feet," and the same one that appears in verse 6, where the woman's road is precisely what cannot be weighed. A man is asked to weigh his way; one road makes weighing impossible; God weighs it all regardless.
The third is the word behind "immoral." In verse 3 the NKJV footnotes it: literally a strange woman. The Hebrew term means other, outside, not-yours, and it runs through the chapter attached to strangers who consume a man's wealth (v. 10) and strangers who must not share what is his (v. 17). This matters for how the chapter is read. It is not a verdict on women, and the catalog must not let it become one. The word describes a relationship, not a character type: she is the woman who is not his. The father is not teaching his son that women are dangerous. He is teaching him what his own appetite will do with an opportunity, and every consequence listed in verses 9 through 14 lands on the son, not on her.
One more thing should be said plainly, because this chapter has been used badly. It is preventive literature, spoken at a fork the son has not yet reached, and its power is in arriving early. For a reader who is already past that fork, the chapter's warnings describe a road already walked, and the word that reader needs is not this lecture but the one Jesus spoke to a woman dragged in from exactly this sin: neither do I condemn you. Both are true. The warning stands at full strength for the one still choosing, and the door stands open for the one who did not heed it.
What this verse contributes
This verse names the goal in guarding language. "Keep" is the same verb the previous chapter made famous at 4:23, "keep your heart," and here it is the lips doing the keeping. The order is deliberate: what a man has thought through in advance is what his mouth has available when he is standing in a doorway being spoken to in honey. Discretion is not quick-wittedness. It is preparation, done early, and the footnote's gloss for the first line is worth having: appreciate good judgment, which is what a man does before he needs it.
Related: Proverbs 4:23 · Proverbs 2:10–11
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.