קְדֹשִׁים תִּהְיוּ כִּי קָדוֹשׁ אֲנִי ה’ אֱלֹהֵיכֶם – You shall be holy, because I, the Lord, your God, am holy. (19:2)
The Midrash in Vayikra Rabba points out that Hashem did not say “Be קָדוֹשׁ, like I am קָדוֹשׁ”, but rather, “Be קָדוֹשׁ , because I am קָדוֹשׁ”. Hashem cannot tell us to be like Him, as Hashem’s קדושה is greater than ours.
Rav Shach quotes the Rambam which explains that we are instructed to perform the mitzva והלכת בדרכיו (Devarim 28:9) – to emulate Hashem’s ways. It would seem that since the pasuk said אֲנִי ה’ אֱלֹהֵיכֶם , the instruction was to be קָדוֹשׁ specifically because we are meant to attempt to be more spiritually inclined, which is what the Midrash addresses.
Rav Shach then contrasts this with a later halacha, which clarifies the previous one. The Rambam states that a person who removes himself from day to day life, refrains from eating meat or drinking wine, and has limited contact with people, is still following the wrong path, and it is forbidden to behave in such a manner.
As such, even though we are meant to emulate Hashem’s ways, we are incapable of being separate from existence in the way Hashem is. As the Midrash said; “Hashem’s קדושה is greater than ours.” Our ability to be קָדוֹשׁ is confined to this world, and it is only through this world that we can attain קדושה . R Shach thus explains that our attempts at והלכת בדרכיו with regard to קדושה is only because Hashem is קָדוֹשׁ , but we are incapable of being like Hashem.
The Aruch HaShulchan wonders why the subsequent pasuk is juxtaposed to אִישׁ אִמּוֹ וְאָבִיו תִּירָאוּ וְאֶת שַׁבְּתֹתַי תִּשְׁמֹרוּ אֲנִי ה’ אֱלֹהֵיכֶם – Every man shall fear his mother and his father, and you shall observe My Shabbosos – I am the Lord, your God. (19:3)
The Aruch HaShulchan explains that in the Ten Commandments, כבד את אביך and שמור את יום השבת were followed by כאשר צוה ה – As Hashem commanded. The reason this is so is that the people who gave you life, cared for you, and made you as a person, are logically deserving of respect. Equally, a day off of work makes a lot of sense too! A rested, happy, worker is more productive. The pasuk therefore stresses that we are not to perform these actions as logical decisions, but rather, kasher tziva hashem.
[It is worth noting that the first set of Luchos did not contain these last few words. The first set of Luchos were made entirely by Hashem (as opposed to hewn from actually rock by Moshe, like the second ones). It seems that Torah learned from the first set of Luchos would never be forgotten, and the people would become like angels. This is why Moshe did not forget the Torah, and why his face shone when he came down the first time at Har Sinai. The first set of Luchos was meant for people who would become like angels – there was no need to tell them כאשר צוה ה.]
This is why the pasuk also attached כאשר צוה ה – through doing these mitzvos purely because כאשר צוה ה, and אֲנִי ה’ אֱלֹהֵיכֶם ,we become קְדֹשִׁים תִּהְיוּ. This can be a reference point to us for all mitzvos – when we want to become קָדוֹשׁ, it is not purely through spirituality that we can do so, echoing what Rav Shach taught. By “taking a day off”, and observing Shabbos Kodesh, we become קָדוֹשׁ. This further brings the words of the Midrash to life, that “Hashem’s קדושה is greater than ours” – precisely because our קדושה is to be found in the physical,