As previously discussed, there is a different psalm recited every day of the week. But it is not perfectly clear what there is about a given psalm that links it to the day it is recited. That is certainly true of the Psalm for Shabbat (Ps 92). The psalm is quite beautiful, and expansive of topic: how satisfying it is to praise G-d; the wonders of creation; the ultimate downfall of the wicked; and the tranquility that awaits the righteous in “the courts of our G-d.”
But what does any of this have to do with Shabbat in particular? There are as many answers as there are rabbis, which is a long way of saying we don’t know. But the answers offered are beautifully suggestive. “I sing of joy of your creation” immediately brings to mind the image of G-d resting on the seventh day, reviewing all that G-d had made, and declaring it was “very good.” We too, it is suggested, should use the Sabbath as a time of rest, reflection, and appreciation.
My teacher Rabbi Reuven Hammer z”l listed a number of other options. Rashi says that the psalm is describing the messianic time when “The righteous shall flourish like the palm tree, they shall grow tall like a cedar in Lebanon.” And since Shabbat is “like the world to come”, it is a foretaste of that messianic time.
An alternative is to link the psalm not to the end of time, but to its beginning. Adam, the midrash tells us, sinned, is punished, and is forgiven on that first fateful Shabbat, and responded by reciting this psalm. There is something especially poignant about Adam, in exile from the Garden of Eden, proclaiming that the righteous will be “planted in the house of the Lord”, and “bear fruit even in old age”—privileges that Adam has lost through disobedience.
In the Yerushalmi Talmud, it links the 7 mentions of G-d’s name to the 7 paragraphs of the Shabbat amidah (remember, the Shabbat amidah has 3 opening and 3 closing blessings, and one in the middle, whereas the weekly amidah has the same opening 3 and closing 3, but 13 blessings in the middle).
Finally, perhaps the most daring idea is incorporated in the Shabbat morning service, where it states that Psalm 92 is not a psalm sung about Shabbat, but rather a psalm sung by Shabbat—the day itself praises G-d. This may sound somewhat outlandish, but I would point out that recent studies of consciousness have inclined to claim that all things, including inanimate objects, have some consciousness. Well, if a rock that just sits there can be conscious, why not a sacred day that brings joy and tranquility to millions?