English Basic Explanation - Chapter 150
This chapter, the final of the 150 Psalms that comprise the Book of Tehillim, begins with a directive to praise the Almighty "in His holy place" and "in the firmament of His strength." While some commentators explain this as a summons to the heavenly bodies to give praise to God (as in the first half of chapter 148), others (including Rabbi Yehuda Halevi, as cited by Ibn Ezra; see also Targum) claim that David actually refers here to the Bet Ha'mikdash. He turns to the Levi'im, who were assigned the role of playing music and singing as accompaniment to the Temple rituals, and urges them to perform their task with immense joy and devotion, recognizing the importance of giving praise to God.
This second approach would explain why David lists numerous categories of instruments in the subsequent verses (3-5). He speaks here to the Levi'im who were given these instruments for the purpose of accompanying the service in the Mikdash with beautiful and inspirational music. If so, then this chapter is not a general summons to all people to give praise to God, but rather a specific exhortation to the Levi'im in the Bet Ha'mikdash.
The final verse of this chapter is a most appropriate conclusion to the Book of Tehillim, in that it encapsulates the essential theme of this entire book: "Every soul shall praise God." One of the fundamental lessons of Tehillim is God's absolute control over all creatures and over all events that take place in the world, which results in our complete dependence on Him for all our needs, including our very existence. David thus concludes this book by declaring that every soul, anyone who breathes, who is graced with the blessing of life, bears an obligation to give praise to God. Even during times of hardship, when the poems of Tehillim are traditionally recited and studied, it behooves us to feel a genuine sense of gratitude to God for all that we have, rather than focus our minds exclusively on that which we still hope to obtain.