The Midrash (Midrash Tehillim 92) relates that after Adam was forgiven for his sin of eating the forbidden fruit in Gan Eden, he sang a song – a song known to us as "Mizmor Shir La'Yom Ha'Shabbat," the 92 chapter of Tehillim. It was on Shabbat that Adam was told that he was forgiven, and so he sung this special song about Shabbat. Appropriately, we recite this chapter as part of our Kabbalat Shabbat service at the onset of Shabbat on Friday night, and this chapter has been designated as the "Shir Shel Yom" for Shabbat, the Psalm associated with this day of the week. Strikingly, however, when we read this chapter, it does not speak about Shabbat at all. After the introductory verse, which identifies this chapter as the special Psalm for Shabbat, there is no mention of Shabbat whatsoever. Why, then, is this the song especially composed for Shabbat? To answer this question, let us briefly examine what this chapter does talk about. The opening verses emphasize that we are to praise and express gratitude to Hashem under all circumstances. "Le'hagid Ba'boker Hasdecha, Ve'emunatecha Ba'lelot" – "To speak of Your kindness in the morning, and Your faith in the nights" (92:3). We must praise Hashem not only in the "daytime," when we enjoy the "light" of joy and good fortune, but also "in the nights," when we find ourselves engulfed by darkness, beset by troubles and hardships. Later, this chapter addresses the famous, baffling reality that the righteous often suffer while the wicked often prosper. Adam here assures us that the righteous will ultimately receive their due reward, whereas the wicked will receive their due punishment. This chapter is associated with Shabbat because the weekly Shabbat that we observe offers us a glimpse of the eternal Shabbat – the next world, when we will achieve perfect clarity and will see how everything is for the best. The Gemara (Pesahim 50a) teaches about the difference between our world and the next world. Here in this world, we celebrate good fortune by reciting the blessing, "Ha'tob Ve'ha'metib," thanking Hashem for His goodness, but when misfortune strikes, Heaven forbid, we solemnly recite "Dayan Ha'emet," acknowledging G-d as the "true Judge." In the next world, however, we will jubilantly recite "Ha'tob Ve'ha'metib" over all events that transpire. The Tzelah (Rav Yechezkel Landau of Prague, 1713-1793) explains this to mean that in the future, we will look back upon all the misfortunes that took place and realize how they were, in fact, good. We will be shown how everything was for the best – even the tragic, painful events that we experienced. In our world, we rightfully mourn and grieve when misfortune strikes. But we must believe that the time will come when we will be shown how ultimately, everything was, in truth, for the best. On Shabbat, we are lifted ever so slightly up from our world, and brought into a different reality – into a realm called "Me'en Olam Ha'ba," a "miniature" Olam Ha'ba (the next world), where we experience a small degree of the clarity of the next world. If we observe Shabbat properly, we receive a boost of Emuna, a greater level of serenity, more emotional strength to accept the challenging aspects of our lives and enjoy happiness and contentment. The precious gift of Shabbat offers us more than a day off from work, and an opportunity to spend more time with family and friends – as significant as this of course is. The gift of Shabbat is the gift of Emuna, the gift of peace of mind. We are able to experience – to some small degree – the faith and unbridled joy of Olam Ha'ba. This is why the chapter written by Adam is chosen as the special Psalm for Shabbat. This is the day when, more than on any other, we are able to deeply feel that "Tob Le'hodot L'Hashem U'l'zamer Le'shimcha Elyon" – that it is good to thank and praise Hashem, that everything He does is for our benefit, even when we face hardship. This weekly boost of Emuna gives us the strength we need for the coming week, fortifying us with the belief that no matter what challenges we confront, everything that happens is for the best.