English Basic Explanation - Chapter 15
David here outlines the virtues that render a person worthy of dwelling in Hashem's "tent" and residing in His "sacred mountain." According to the Radak, David refers here to the resting place of the soul in the afterlife; it is thus here where we are told how a person earns his eternal share in the world to come. The Radak draws proof to this reading from the chapter's final clause, where David exclaims, "he who does these shall not falter, forever." The term "forever" implies that David refers here to eternal peace, which would suggest that he speaks of the soul's reward in the afterlife.
In listing these virtues, David focuses first on proper interpersonal conduct: honesty and integrity (verse 2), and refraining from crimes such as gossip, causing others harm, and nepotistic protection of unworthy relatives (verse 3). In verse 4, he imposes an important qualification on the virtues of loving kindness and concern for others: "Nivzeh Be'einav Nim'as," which Rashi translates to mean, "The shameful one is despicable in his eyes." Although this prototype acts with love and sensitivity, he is at the same time prepared to confront evil and its advocates, rather than extend to them the same kindness and compassion he shows generally. He respects those who deserve respect, while condemning behavior that warrants condemnation.
The Ibn Ezra and Radak explain this verse differently, as meaning that the person sees himself as "shameful" and "despicable." Despite his many fine qualities, he recognizes how much more he has to grow and accomplish in order to achieve perfection. Rather than falling into the trap of stifling complacency, he constantly strives to improve and to accomplish more.
The message conveyed by this Psalm is thus a dual one. On the one hand, David promises eternal life to everyone who lives in accordance with the basic values of honesty and Godliness; the world to come is not reserved for only the great Tzadikim who have reached the highest levels of spiritual devotion. At the same time, however, to earn eternal life one must spend his life in the pursuit of perfection, working each day to grow and become better than he is. This Psalm does not demand that everybody be perfect, but it does not demand that everybody work towards and strive for spiritual perfection.