Agur claims no great intelligence or superior understanding. He feels his education is lacking in the more important areas of life, like the proper way to live and the knowledge of God. He is only a common man with no special abilities, powers or privileges—in fact, he would like to know the person who could do some of these things.
In verses 5 and 6 he states his conclusion: To get the most and the best from life, we should believe God, not presuming that we can comprehend the effects of our actions without advice from God in His Word. God's Word cannot be improved upon; every word of God is pure, as gold and silver are pure (Psalm 12:6). The value of God's Word cannot be increased by adding to or taking from it, anymore than gold can be increased in value by alloying it with something else. He advises that we strive to do nothing that God forbids and leave nothing undone that God commands. This is the approach of a man whose sole aim is to please God, and who does not want to do or not do anything that might strain the relationship.
John W. Ritenbaugh
Christmas, Syncretism, and Presumption
The word "pure" might be better translated "refined." Its background is putting something to the test and it works. The advice has been refined; it is as pure as it can be. Then he adds, "Don't add to it, and it will be a shield to you."
Why will it protect us?
As for God, His way is perfect; the word of the LORD is proven [similar to refined, tested, pure]; He is a shield to all who trust in Him. (Psalm 18:30)
Protection from what? We need protection from all of the things that bondage and sin imply. If we lack the refined, pure, unadulterated Word of God, the only alternative is the word of men! Nowhere in God's Word does He says the word of men is pure, true, or refined. The word of men is limited to the experiences of men and by their prejudices. Even though a man may try, with all sincerity, to report something as honestly and accurately as he can, he does not have the breadth of experience or the unprejudiced mind of God.
If we trust the words of men in place of the words of God, we will not be protected from bondage. We will slide back into it.
John W. Ritenbaugh
Freedom and Unleavened Bread
Other Forerunner Commentary entries containing Proverbs 30:6: