(In his renowned maamar entitled VeKibeil HaYehudim,1 delivered on Purim Katan, 56872) my revered father-in-law, the Rebbe Rayatz explainsוּמְבָאֵר כ"ק מו"ח אַדְמוֹ"ר (בְּמַאֲמָרוֹ הַיָּדוּעַ דִּבּור הַמַּתְחִיל וְקִבֵּל הַיְּהוּדִים שֶׁנֶּאֱמַר בְּפוּרִים קָטָן תרפ"ז),
that tzivui, the Hebrew word for “command,” relates to the word tzavsa, which means “connection” or “bond.”3דְּצִוּוּי (תְּצַוֶּה) הוּא צַוְתָא וְחִבּוּר.
Thus the verse, “And you shall command the Children of Israel,” carries with it the implication thatוְזֶהוּ "וְאַתָּה תְּצַוֶּה אֶת בְּנֵי יִשְׂרָאֵל",
Moshe binds and connects the Jewish people with the Or Ein Sof, G‑d’s infinite light.4שֶׁמֹּשֶׁה הוּא מְקַשֵּׁר וּמְחַבֵּר אֶת בְּנֵי יִשְׂרָאֵל עִם אוֹר אֵין סוֹף.
At the beginning of sec. 4 of the maamar entitled VeKibeil HaYehudim, 5687 (and similarly, at the beginning of sec. 15), the Rebbe Rayatz mentions a similar, but not identical concept, that Moshe strengthens the connecting bonds within the Jewish people, and thereby heightens their unity. The Rebbe Rayatz does not, however, mention that Moshe connects the Jews with the Or Ein Sof.
It is possible to explain that in the maamar of the Rebbe Rayatz, the emphasis is on the connection Moshe establishes within the Jewish people, as will be explained in sec. 11 of the present maamar.
Moshe’s efforts to draw down influence to the Jewish people (and thus connecting them with the Or Ein Sof)וְעַל יְדֵי שֶׁמֹּשֶׁה מַשְׁפִּיעַ לְיִשְׂרָאֵל (שֶׁמְּקַשֵּׁר אוֹתָם עִם אוֹר אֵין סוֹף),
increases and enhances Moshe’s own spiritual power.עַל יְדֵי זֶה נַעֲשֶׂה יִתְרוֹן וְהוֹסָפָה בְּמֹשֶׁה.
[For the relationship between Moshe and the Jewish people can be described by the analogy of the head and the feet of a human body,[דְּמֹשֶׁה וְיִשְׂרָאֵל הֵם דֻּגְמַת רֹאשׁ וְרֶגֶל,
as it is written,5 “Here I am in the midst of 600,000 people on foot.”כְּמוֹ שֶׁכָּתוּב "שֵׁשׁ מֵאוֹת אֶלֶף רַגְלִי הָעָם אֲשֶׁר אָנֹכִי בְּקִרְבּוֹ",
Implied is that the Jewish people are the feet of Moshe, as it were,דְּכָל יִשְׂרָאֵל הֵם הָרַגְלַיִם דְּמֹשֶׁה,
and that he is their head.וּמֹשֶׁה הוּא הָרֹאשׁ שֶׁלָּהֶם.
In human terms, on an obvious level, the head elevates the functioning of the feet. Nevertheless, the feet also contribute to the head, forוּכְמוֹ שֶׁבָּאָדָם
the feet can bring the head to places to which it could never reach on its own.הָרַגְלַיִם מוֹלִיכִים אֶת הָרֹאשׁ לַמָּקוֹם שֶׁהָרֹאשׁ מִצַּד עַצְמוֹ אֵינוֹ יָכוֹל לְהַגִּיעַ לְשָׁם,
Similarly in regard to the relationship between Moshe and the Jewish people —כְּמוֹ כֵן הוּא בְּמֹשֶׁה וְיִשְׂרָאֵל,
Of course, Moshe elevates the Jewish people, but also
through the Jewish people (i.e., Moshe’s feet),שֶׁעַל יְדֵי יִשְׂרָאֵל (הָרַגְלַיִם דְּמֹשֶׁה)
Moshe is advanced to a higher level.מִתּוֹסֵף עִלּוּי בְּמֹשֶׁה,
The above concepts allow for an extended interpretation of the above verse.דְּזֶהוּ מַה שֶּׁכָּתוּב
The word the verse uses for “I” is Anochi, the level of G‑dliness so transcendent that it cannot be given a name. The verse,
“Here I am in the midst of 600,000 people on foot”"שֵׁשׁ מֵאוֹת אֶלֶף רַגְלִי הָעָם אֲשֶׁר אָנֹכִי בְּקִרְבּוֹ",
can thus be interpreted to mean: Because of the 600,000 people on foot, the revelation of the level of Anochi is drawn down in Moshe’s midst.]6שֶׁעַל יְדֵי רַגְלֵי הָעָם נִמְשָׁךְ הַגִּלּוּי דְּאָנֹכִי בְּקִרְבּוֹ שֶׁל מֹשֶׁה].
Moshe operated on a high spiritual rung. Nevertheless, Anochi, which refers to the Sefirah of Kesser, and on a higher level, to G‑d’s Essence, was beyond his reach. Only through the influence of the Jewish people as a whole was he able to attain that rung.
Based on the above, we can understand the verse, “And you shall command the Children of Israel, and they shall bring you pure olive oil….”וְזֶהוּ "וְאַתָּה תְּצַוֶּה אֶת בְּנֵי יִשְׂרָאֵל וְיִקְחוּ אֵלֶיךָ שֶׁמֶן זַיִת" גוֹ',
Through Moshe’s efforts to connect and bind the Jews with the Or Ein Sof,דְּעַל יְדֵי שֶׁמֹּשֶׁה יְצַוֶּה וִיקַשֵּׁר אֶת בְּנֵי יִשְׂרָאֵל עִם אוֹר אֵין סוֹף,
the Jews will be motivated to bring olive oil to Moshe (i.e., “and they shall bring you”),עַל יְדֵי זֶה יָבִיאוּ בְּנֵי יִשְׂרָאֵל שֶׁמֶן זַיִת לְמֹשֶׁה (וְיִקְחוּ אֵלֶיךָ),
bringing about an increase of light for Moshe.שֶׁיּוֹסִיפוּ תּוֹסְפוֹת אוֹר בְּמֹשֶׁה.

Summary

The verse, “And you shall command (tetzaveh) the Children of Israel,” carries with it the implication that Moshe binds and connects (as in the term tzavsa) the Jewish people with the Or Ein Sof, G‑d’s infinite light. Building on that concept, it can be explained that the relationship between Moshe and the Jewish people can be described by the analogy of the head and feet of a human body. The head elevates the functioning of the feet. Nevertheless, the feet also contribute to the head, for the feet can bring the head to places it could never reach on its own. Similarly, Moshe elevates the Jewish people, but also through the Jewish people, Moshe is advanced to a higher level.