The section of our service known as the Tefillah (it's also known as the Amidah or the Shemona Esrei) follows a distinct pattern. It opens and closes with three blessings, and those blessings are meant, in large part, to act as a frame for what comes in-between. During the week, that middle part contains 13 (or, in our prayerbook, 12) requests - requests for health, wisdom, salvation, and so on. On Shabbat, we replace those requests with one prayer, a prayer which asks for nothing, but instead acknowledges the holiness of Shabbat.
The traditional reason given for this Shabbat alternative is that it's innapropriate to ask for something on Shabbat. Shabbat is supposed to be the time when we act as if the world is perfect, and we want for nothing. Making a request of God would break that illusion, so we don't do it.
While looking at these prayers this past Shabbat, before I talked about the traditional reasoning for the Shabbat Amidah, I asked if anyone there had any theories as to the reason behind the change. Someone suggested that perhaps it was because God deserved rest, too - it would be improper to distrub God's Shabbat with a request.
In a way, it's the same answer, but also very different, because it puts the focus on God, not on us. I had never heard this take on it before, and I found it wonderful - insightful, but also lovely. Of course, we can't literally ruin God's Shabbat. But, metaphorically, I think it's powerful to think of Shabbat as so sacred, that simply bugging God with our concerns is illegal.
Shabbat can offer so much to us, personally. But, when we start looking out for others as well, we might start to truly make Shabbat more than restful. We might make it holy, as well.