The concept of the two missions—the mission to engage in the mundane world during the weekdays, and the mission to refrain from work on Shabbos, but to appreciate that we’re given everything from Hashem—also applies to the avodah of tefillah.
When we daven, there are two aspects. There’s the “weekday” aspect, and there’s the “Shabbos” aspect. In the intermediate berachos of Shemoneh Esrei, we speak of our lack, whereas in שלום שים we speak of the light of Hashem’s Face, as it were—which connotes completeness and perfection—and this is the Shabbos avodah.
Climbing the Ladder
From Above, we’re placed into a situation in which we will feel lack—but the Ribbono shel Olam wants us to introduce “Shabbos” into this equation, that is, to climb the ladder that culminates with Shabbos. A Yid begins the climb in this lowly world, but he reaches for Shabbos, מעין הבא עולם. Throughout עשרה שמונה, he expresses his lack.... He’s lacking wisdom, health, blessing, etc., and he asks for those needs. But the story concludes with שלום: שים “Ribbono shel Olam! Give me the light of Your countenance! For when I receive this, I will have everything!”
