Rashi on Numbers 11:16/רש"י על במדבר י״א:ט״ז

1אספה 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).

2אשר 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).

3ולקחת 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).

4והתיצבו 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).