Chasidut do Powtórzonego Prawa 26:1

And it will be, when you come etc. (Deuteronomy 26:1) - it is important to explain that behold, there are two levels of righteous people. There is the righteous that serves G!d out of awe all days of the wee, and when the Holy Shabbat comes an extra holiness is added to that righteous one, that s/he serves G!d out of love, and through that the righteous one comes to the level of love. And there is the righteous person that also during the days of the week serves G!d out of love, and this righteous one is called with the name Shabbat, as we find in the Holy Zohar “a disciple of the sages is called Shabbat”, that is, Shabbat is the aspect of love, and this righteous person is always at this level, therefore s/he is also called Shabbat.