אספה לי. הֲרֵי תְשׁוּבָה לִתְלוּנָתְךָ שֶׁאָמַרְתָּ לֹא אוּכַל אָנֹכִי לְבַדִּי; וְהַזְּקֵנִים הָרִאשׁוֹנִים הֵיכָן הָיוּ? וַהֲלֹא אַף בְּמִצְרַיִם יָשְׁבוּ עִמָּהֶם, שֶׁנֶּאֱמַר (שמות ג') "לֵךְ וְאָסַפְתָּ אֶת זִקְנֵי יִשְׂרָאֵל"? אֶלָּא בְּאֵשׁ תַּבְעֵרָה מֵתוּ; וּרְאוּיִים הָיוּ לְכָךְ מִסִּינַי, דִּכְתִיב "וַיֶּחֱזוּ אֶת הָאֱלֹהִים" (שם כ"ד) — שֶׁנָּהֲגוּ קַלּוּת רֹאשׁ כְּנוֹשֵׁךְ פִּתּוֹ וּמְדַבֵּר בִּפְנֵי הַמֶּלֶךְ, וְזֶהוּ "וַיֹּאכְלוּ וַיִּשְׁתּוּ", וְלֹא רָצָה הַקָּבָּ"ה לִתֵּן אֲבֵלוּת בְּמַתַּן תּוֹרָה וּפָרַע לָהֶם כָּאן (תנחומא): אספה לי GATHER UNTO ME [SEVENTY MEN OF THE ELDERS OF ISRAEL] — "This" — the Lord said — “is the reply to your complaint which you uttered (v. 14) I am not able to bear all this people alone”’ (cf. Sifrei Bamidbar 92). But where were the first elders, that God commanded him to gather elders anew? Had they not sat as judges together with them (with Moses and Aaron) in Egypt, as it is stated, (Exodus 3:16) “Go and gather the elders of Israel together”? But these had died by the consuming fire of Taberah (v. 3). They really had deserved this for their conduct at Sinai, as it is said, (Exodus 24:11) "And they beheld God” which means, that they comported themselves irreverently towards God — like a person who nibbles his bread and at the same time addresses the king — for this is the meaning of the words, “[And they saw God] and ate and drank”. The Holy One, blessed be He, however, did not wish to give any cause for mourning at the joyous event of the Lawgiving, and therefore punished them here (at Taberah) (Midrash Tanchuma, Beha'alotcha 16).
אשר ידעת כי הם וגו'. אוֹתָן שֶׁאַתָּה מַכִּיר שֶׁנִּתְמַנּוּ עֲלֵיהֶם שׁוֹטְרִים בְּמִצְרַיִם בַּעֲבוֹדַת פֶּרֶךְ וְהָיוּ מְרַחֲמִים עֲלֵיהֶם וּמֻכִּים עַל יָדָם, שֶׁנֶּאֱמַר "וַיֻּכּוּ שֹׁטְרֵי בְנֵי יִשְׂרָאֵל" (שמות ה'), עַתָּה יִתְמַנּוּ בִגְדֻלָּתָן כְּדֶרֶךְ שֶׁנִּצְטַעֲרוּ בְּצָרָתָן (עי' ספרי): אשר ידעת כי הם וגו׳ WHOM THOU KNOWEST TO BE [THE ELDERS OF THE PEOPLE, AND BAILIFFS OVER THEM] — i.e. them whom thou knowest to have been appointed officers (שמרים) over them (the Israelites) in Egypt in connection with the rigorous labour imposed on them, but they pitied them and were smitten by the Egyptian taskmasters on their account — as it is said, (Exodus 5:14) “and the officers of (שמד) the children of Israel were smitten”. Now they were to become officers in their greatness (now when the Israelites had become great) just as they had suffered when they (the Israelites) were in distress (cf. Sifrei Bamidbar 92).
ולקחת אתם. קָחֵם בִּדְבָרִים, "אַשְׁרֵיכֶם שֶׁנִּתְמַנִּיתֶם פַּרְנָסִים עַל בָּנָיו שֶׁל מָקוֹם": ולקחת אתם AND TAKE THEM [UNTO THE APPOINTED TENT] — win them over with fine words: “Happy are you that you are appointed chiefs over the children of the Omnipresent God” (cf. Sifrei Bamidbar 92).
והתיצבו שם עמך. כְּדֵי שֶׁיִּרְאוּ יִשְׂרָאֵל וְיִנְהֲגוּ בָהֶם גְּדֻלָּה וְכָבוֹד, וְיֹאמְרוּ חֲבִיבִין אֵלּוּ שֶׁנִּכְנְסוּ עִם מֹשֶׁה לִשְׁמֹעַ דִּבּוּר מִפִּי הַקָּבָּ"ה (שם): והתיצבו שם עמך AND LET THEM PLACE THEMSELVES THERE WITH THEE, in order that the Israelites may see it and do them high esteem and honour, saying, “Beloved indeed must these be since they may enter together with Moses to hear Divine utterance from the mouth of the Holy One, blessed be He!” (Sifrei Bamidbar 92).