Chapter 16 of Rabbi Shloma Majeski’s Likkutei Mekoros, Volume 2, responds to the questions: Where does the Rebbe explain why he refers to the Pervious Rebbe when he actually means himself? Where does the Rebbe state that he and the Previous Rebbe are one and the same? (Underlined text is the compiler’s emphasis.)
Translated and presented by Boruch Merkur
23. […] Earlier it was mentioned (Section 9) that Shabbos is the time for the study of p’nimius ha’Torah, the inner dimension of the Torah. “Shpitz Chabadniks” may be inclined to interpret this statement to mean that on Shabbos we don’t need to study Nigla, or that it is forbidden outright. It is decidedly not so. The Chassidishe schedule for Shabbos, rather, demands that, in addition to two thirds of one’s study time being devoted to Chassidus, one third is for the study of Nigla. (See Footnote 49 in original for sources.)
In this vein, my revered father in-law, the Rebbe, tells of his father, the Rebbe [Rashab], nishmaso Eden, that on Shabbos, and even on Yom Kippur, he would maintain his daily study schedule, which of course, included the study of Nigla. On a different occasion, the Rebbe, my father in-law, specified the material he learned.
In fact, the Rebbe [Rayatz] had the same practice [as his father, the Rebbe Rashab, to study a third Nigla on Shabbos], but since in general the Rebbe would speak very little about himself, when he wished to say something about himself he would do so by speaking of his father.
Nigla is to be learned even on Yom Kippur, which is Shabbos Shabbason. Certainly then on a regular Shabbos we must learn Nigla (in addition to reciting Eizehu Mekoman, prior to davening).
Nigla entails birurim (refining the world by being within it and elevating it – see Footnote 52 in original for sources), but the malacha of birur (the action of separating or selecting) is prohibited on Shabbos. Thus, it was mentioned earlier that on Shabbos we don’t learn the portion of Torah that speaks about mundane matters (voch’dike zachen). The meaning of this [in light of what we said regarding the need to learn one third Nigla on Shabbos] is that the Nigla of Shabbos is on a higher plane. It is beyond the concept of birurim just as eating on Shabbos is not an instance of birurim, as it is during the week; on Shabbos eating is elevated.
(From the address of Shabbos Parshas Shmos 5713, Shabbos Mevarchim Chodesh Shvat; Sichos Kodesh 5713, pg. 137)