This verse closes the opening movement of the father's lecture on wisdom and the neighbor, Proverbs 3:21–35.
Quick answer
The reason the wise can walk safely and sleep unafraid: the LORD Himself is their confidence. The security of vv. 21–25 was never self-assurance.
Read the whole unit
The father's lecture on wisdom and the neighbor moves in three sweeps. First, security (vv. 21–26): keep sound wisdom in view and the results are bodily and immediate, safe steps, unafraid nights, sweet sleep, because "the LORD will be your confidence." Second, the neighbor (vv. 27–31): five consecutive "do nots" that bring wisdom down from the cosmos of the preceding poem to the person next door. Do not withhold good that is owed, do not delay it until tomorrow, do not plot against the neighbor who trusts you, do not pick fights, and do not envy the violent man who seems to be winning. Third, the reasons (vv. 32–35): four verses that ground neighbor-ethics in the LORD's own stances, His abomination and His intimacy, His curse and His blessing, His scorn and His grace, and the divergent inheritances of the wise and the foolish. Some scholars divide the passage at v. 27, treating the neighbor commands as their own unit; the flow of thought holds together as one lecture, since the "do nots" rest directly on the security just described (a person confident in the LORD can afford to be generous and unenvious) and the closing verses supply the reasons for both halves. This entry set treats 3:21–35 as one lecture and notes the boundary question honestly here, once.
What this verse contributes
The "for" that opens this verse corrects a possible misreading of the whole section as self-help. The safe walk and the sweet sleep rest on the LORD, who keeps the foot that could not fully keep itself, and the verse quietly closes the loop 3:5 opened: lean not on your own understanding, because there is Someone rated for the load. The snare image is apt: snares are the dangers you do not see. Wisdom handles the visible stones (v. 23); the LORD handles the hidden traps.
Related: Proverbs 3:5–6 · Psalm 91:3
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.