Albert Barnes Commentary Proverbs 6:21-22

"Bind them continually upon thy heart; Tie them about thy neck. When thou walkest, it shall lead thee; When thou sleepest, it shall watch over thee; And when thou awakest, it shall talk with thee." — Proverbs 6:21-22 (ASV)

The thought of Proverbs 3:3 is carried a step further. No outward charm, but the law of obedience, shall give safety to the traveler, when he sleeps or when he wakes.