Midrasch zu Bamidbar 11:14

24 (Numb. 11:16) “Gather Me [seventy men from the elders of Israel]”: But did you not have elders before? Here now it is written concerning Mount Sinai (in Exod. 24:9), “Then there went up Moses […] and the seventy elders of Israel”; and this parashah (with Numb. 11:16) comes after that. So where were the[se earlier] elders? It is simply that, when Israel did those things which are stated (in Numb. 11:1), “Now the people were as murmurers […] then the fire of the Lord burned against them,” they were all destroyed by fire at that time. It is simply that their burning was like the burning of Nadab and Abihu, for they also had acted with disrespect on ascending Sinai, when they saw the Divine Presence. It is so stated (in Exod. 24:11), “they beheld God, and they ate and drank.” Was there eating and drinking there? To what is the matter comparable? To a servant who attended his master while [holding] a slice of bread in his hand and taking bites from it. Similarly had they acted with disrespect as though eating and drinking. So the elders along with Nadab and Abihu deserved to be destroyed by fire on that day; but because the giving of Torah was dear to the Holy One, blessed be He, He therefore did not want to harm them and bring calamity to them on that day. This is what is written (ibid.), “But He (the Holy One, blessed be He,) did not raise His hand against the nobles of the Children of Israel.” From this you may infer that they deserved to have a hand raised [against them]. After a time, however, He collected their debt: Nadab and Abihu were also destroyed by fire as they entered the tent of meeting, while the elders were destroyed by fire when they were filled with lusting, as stated (in Numb. 11:4), “Then the rabble (ha'safsuf) which was in their midst became filled with lust.” Who were the rabble (ha'safsuf)? R. Simeon ben Menasya and R. Simeon bar Abba [differed on the matter]. One said, “These were the proselytes who came up with them from Egypt and who were gathered (ne'esafim) together with them as stated (in Exod. 12:38), ‘And a mixed multitude went up with them.’” But the other said, “Rabble can only be a Sanhedrin, since it is stated (in Numb. 11:16), ‘Gather (esfah) Me seventy men.’” What [else] is written there (in Numb. 11:1)? “Then the fire of the Lord burned against them and consumed them in the outskirts (qetseh) of the camp,” [i.e.,] among the selected (muqetsim) in the camp. And where is it shown that those elders who went up onto the mountain were destroyed by fire? Where it is stated (in Ps. 106:18), “And fire broke out in their company ('edah),” since company ('edah) can only be a Sanhedrin as stated (in Numb. 15:24), “And it shall come to pass that if it was done [by mistake] away from the eyes of the congregation ('edah).”⁵¹I.e. the leaders of the congregation. So Rashi on Numb. 15:24. It is also written (in Lev. 4:13), “And if the whole congregation ('edah) of Israel⁵²This expression was often interpreted as denoting the Sanhedrin. So Sifra to Lev. 4:13 (42: Wayyiqra parashah 4); R. Meir in Hor. 5a; Rashi on Lev. 4:13. should err.” And likewise it says (in Ps. 78:31), “When God’s anger flared up at them, He slew their sturdiest,” these were the Sanhedrin; “struck down the chosen of Israel,” these were the chosen ones that were called elders, about whom it is written (in II Sam. 6:1), “And David still added to the chosen among Israel.” Then they wept again and demanded meat. Now you might say, “What they wanted was animal flesh? Did it not come about that the manna became whatever they wanted inside of their mouths, as stated (in Ps. 106:15), ‘So He gave them what they asked for...’?” And in case you should say that they did not have oxen and cattle in the desert, has it not already stated (in Exod. 12:38), “And a mixed multitude went up with them and flocks and herds.” And in case you should say they ate them in the desert, is it not written (in Numb. 32:1), “Now the children of Reuben and the children of Gad had much livestock?” From here R. Simeon said, “It was not meat for which they lusted, since it says so (in Ps. 78:27) – ‘And He rained down flesh (she'er) upon them like dust.’ Now she'er must denote illicit intercourse since it is stated (in Lev. 18:6), ‘None of you shall approach any close (she'er) relation to him.’ Ergo, it [really] says that they desired to permit illicit intercourse for themselves; and so it says (in Numb. 11:10), ‘Now Moses heard the people weeping for their families.’”⁵³See Yoma 75a according to which they were weeping here because of the family relations with whom they were forbidden to have intercourse. Thus when they desired such [relations] (ibid. cont.), “the Lord was very angry and it was bad in the eyes of Moses.” At that time Moses said to the Holy One, blessed be He, (in vs. 11), “’Why have you mistreated Your servant […]?’ In the past there was one with me who would bear the burden of Israel, but now I am alone.” Thus it is written (in vs. 14-15), “I am not able to bear [all] this people alone…. So if You are dealing like this with me, please truly kill me.” At that time the Holy One, blessed be He, said to him, “Appoint other elders instead of those elders.” It is so stated] (in vs. 16), “Gather Me seventy men.”