Likutei Moharan 79:2/ליקוטי מוהר"ן ע״ט:ב׳

12. {“See that God has given you the Sabbath; that is why I gave you on Friday the food of two days. Every person shall abide below his place; no man shall go out of his place on the seventh day” (Exodus 16:29).} When can a person recognize his own lowliness? On Shabbat. For of Shabbat it is said: “See that God has given you the Shabbat.” ShaBbaT is Shin BaT. Shin is the three colors of the eye; BaT is the bat (pupil) of the eye (Tikkuney Zohar #70, p.126b). Thus on Shabbat he is able to recognize his lowliness.

2This is the meaning of that which was said concerning Shabbat: “Every person shall abide below his place”—i.e., below his level, lower than he actually is. At the very least “no man shall go out of his place”—i.e., reaching beyond his level; for example, by doing as Zimri, and asking for the reward of Pinchas (Sotah 22b). And when on Shabbat can he recognize his lowliness? When he does complete TeShuVah (repentance), which is ShaBbaT, as it is written (Deuteronomy 30:2), “Then ShaVTa (you shall return) to God your Lord.” Their letters are the same.