This is the concept of our Possuk: שוּבָה יִשְרָאֵל עַׁד הַׁוַׁיָ׳ גּוֹ׳,אֶלֹקֶיך כִי כָשַׁלְתָ בַׁעֲוֹנֶיך קְחוּ עִמָכֶם דְבָרִים “Return, Yisroel, to HaShem your G-d, for you have stumbled in your iniquity. Take words with yourselves and return to HaShem”. Specifically, because “you have stumbled in your iniquity” [this results in a situation] that ‘he is walking in the desert’, and that he [now] has the opportunity to take, so to speak, ‘new words’.
For even though the Torah dictates לֹא תוֹסִיף וְלֹא תִגָרַׁע “Do not add – Do not diminish” he has the ability so to speak to take new words, קְחוּ עִמָכֶם דְבָרִים in a ‘periodic additional offerings’ manner, beyond any boundaries or limitations set by the Torah, so that even a day which according to the Torah is not Shabbos a Jew has the ability to make into a Shabbos! What’s more is that on his weekdays he can also draw down holiness as mentioned above.
Even though the above explanation is expounded in Likkutei Torah, so there is the possibility to say that it could only apply to a person, who studies Likkutei Torah and studies it in depth, however, it could also be said that this Avodah is relevant to every single one of Yisroel, for this Possuk is said the Haftorah of Shabbos Shuvah which everyone hears in Shul, including men women and children, so from this it is [self]understood to be relevant to the ‘Avodah’ of [each and] every one of Yisroel.
Furthermore, it has the impetus of Shabbos, for Shabbos is fixed into the nature of the world and the nature of creation as the Talmud states: שַׁבָת מִיקַׁדְשָא וְקַׁיְימָא Every seventh day is automatically Shabbos which means that it is not dependant on the status or standing of the B’nei Yisroel.
There is something wonderous that we can add! This concept of ‘Havaye is your G-d’ comes out in a revealed way on the body of every one of B’nei Yisroel as is explained elsewhere on the Possuk in Tehilim: שִוִיתִי הַׁוַׁיָ׳ לְנֶגְדִי תָמִיד “I have placed ‘Havaye’ before me” that every face has the name of ‘Havaye’ imprinted on it. The ‘eyes’ to see is the faculty of vision (which corresponds to Chochma) is the first letter ‘Yud’; the ‘ears’ to hear is the auditory faculty (which corresponds to Binah) and is the first ‘Hey’; the nose is the letter ‘Vov’ (which looks like a nose) and the mouth is the last letter ‘Hey’ (Symbolising the five types of sounds from the mouth).
