Proverbs 30:5

Every word of God is pure - כל אמרת אלוה צרופה col imrath eloah tseruphah, "Every oracle of God is purified." A metaphor taken from the purifying of metals. Every thing that God has pronounced, every inspiration which the prophets have received, is pure, without mixture of error, without dross. Whatever trials it may be exposed to, it is always like gold: it bears the fire, and comes out with the same lustre, the same purity, and the same weight.

He is a shield unto them - And this oracle among the rest. "He is the defense of all them that put their trust in him." לכל lechol, to all, is added here by nineteen of Kennicott's and De Rossi's MSS.; for instead of לחסים lachosim, to the trusters, they read לכל החוסים lechol hachosim, "to Every One of them that trust." Where the preposition and adjective are not only added, but the noun is written more full, and more emphatic: but a translation cannot well express it without paraphrase.

Out of this consciousness of the impotence of all man's efforts after the knowledge of God rises the sense of the preciousness of every living word that God has Himself revealed, whether through "the Law and the prophets" or through "wise men and scribes."

30:5 Pure - You must not expect the full knowledge of Divine mysteries from me, nor from any man, but from the word of God.