English Basic Explanation - Chapter 133
This Psalm begins with one of the most famous phrases in all of Tehillim: "Behold, how good and pleasant it is when brothers dwell together." The commentators disagree, however, in explaining to whom this verse refers. Rashi claims that David speaks here of the inauguration of the Bet Ha'mikdash, when the Shechina (Divine Presence) finally resided among Bene Yisrael. It was at that time when the "brothers" – the Almighty and the Jewish people – once and for all were able to "dwell together." The Radak, by contrast, claims that David refers here the time of the final redemption. According to the Radak, David describes the harmonious relationship that will exist between the two leaders of the Jewish people – the king and the Kohen Gadol (high priest). Generally, there is a good deal of tension and discord between different branches of government, and between political and religious leaders. During the time of the Messianic era, however, a feeling of peace and brotherhood will prevail such that the nation's political and religious leaders will work and cooperate with each other in perfect harmony and mutual love and respect.
A third approach appears in the Mesudat David commentary, which explains that David speaks here of the entire Jewish nation reuniting in its ancient homeland in peace and unity. Whereas during the First Temple period the nation's unity was ruptured with the formation of a separate kingdom after King Shelomo's death, in the time of Mashiah all Am Yisrael will be harmoniously united under a single kingdom, as we will all join together in the faithful service of the Almighty.
In verses 2 and 3, David draws two analogies to describe the aura of peace and serenity mentioned in verse 1. First, he makes reference to the anointing of Aharon as the Kohen Gadol, which entailed pouring oil onto his head which then dripped down onto his clothing. Thereafter, David speaks of the dew that drips from the towering slopes of Mount Hermon onto the lower hills of Eretz Yisrael. Mesudat David explains that in both of these images, a liquid drips and percolates onto a wide area beneath its point of origin. These images accurately symbolize the idyllic nature of the Messianic era, when the nation's leadership will effectively inspire and influence the masses. Just as the single drop of oil split into many drops that descended upon Aharon's clothing, and the dew falls from the tall mountains onto all the surrounding lower hills, so will the wisdom and spiritual devotion of the Jewish people's leadership be bestowed upon the entire nation. They will provide the guidance and instruction Am Yisrael needs to live a life of devotion to God and His Torah, thereby ensuring that, as this Psalm concludes, we will be deserving of eternal life and blessing.