The Rebbe Rashab explains in a Maamor dated 5679-1919 and opening with the same verse by introducing a familiar concept [in Chassidus] that Moshe is called a ‘faithful shepherd’ because he shepherds and supports the Jewish Neshomohs by means of strengthening them in their faith in Hashem.
He explains at length that; ‘One needs to have complete faith not just at a Divine level of Memalei Kol Almin but also at a level of Sovev kol Almin and even [higher] in Hashem’s Atzmus the infinite light which is spiritually exalted above both Sovev Kol Almin and Memalei Kol Almin.
And it is concerning this, that the Possuk in Tehilim states: אֱמוּנָּׂהוּרְּעֵה “Be nourished by faith” that the faith needs to be shepherded to be internalised.
Accordingly, the Frierdiker Rebbe also explains in his Maamor with the opening words וְּקִּבֵל הַיְּהוּדִּים that he delivered on Purim Koton in the year 5687 - 1927 which he based [largely] on the above-mentioned Maamor of the Rebbe RaShab from the year 5679-1919 (except that his Maamor starts with the words וְּקִּבֵל הַיְּהוּדִּים and the Maamor does not elucidate the Possuk from Parshas Ki Sisah).
The Rebbe RaShaB explains in the Maamor that this Hamshocho through which Moshe Rabeinu causes the faithfulness to be internalised is represented by the concept of the half Shekel of the holy Shekel.
