(1) נבל תבל — Explain this as the Targum does: thou will certainly become weary. Its meaning expresses the idea of withering, old French flestre, just as. (Jeremiah 8:13) “and the leaf is withered (נבל)”; (Isaiah 34:4) “as withereth (כנבל) the leaf from off the vine” — the meaning being that it becomes shrivelled through the heat and through the frost, and so its strength diminishes and it becomes, as it were, weary, and falls from off the vine (מגפן).
(3) כי כבד ממך FOR [THIS THING] IS TOO HEAVY FOR THEE — its weight is far more than thy strength can bear.
(1) נבול תבול, "you will surely become weary, etc." Yitro repeated the word נבול because it has two meanings. We apply this term to describe anything which has lost some of its original strength, and as a result has become weary, fatigued, relative to its original state. Nonetheless the subject under discussion is still able to perform its basic task though with greater exertion. The second meaning of נבול is a feeling of weariness which is felt so keenly that the subject is unable to carry out his regular routine at all. Yitro warned Moses that though, intially, he would feel only slightly weary, eventually he would become so weary, נבול תבול, that he would be unable to function at all. Yitro underlined this by saying: "you will not be able to carry on by yourself." Alternatively, the reason he repeated the word was simply because he wanted to illustrate how both Moses and the litigants would become weary.
(4) Was unable to judge them? Some [commentators] ask: Yisro said to Moshe, “You are going to wear yourself out (Shemos 18:18).” Rashi should have asked [there]: Regarding a prophet like Moshe, how could Yisro think it was difficult for him to judge the People? The answer is that above, I could think that Yisro was saying the following: “You are going to wear out this people.” I.e., it was difficult for the people that Moshe sat alone to judge them, for they all stood waiting for him from morning until evening. Certainly if there were many judges, it would be easier upon the people. Therefore, since it was difficult for the People then they would complain to Moshe, and this would be difficult for him. Therefore, Rashi explains [only] here.
(2) לא תוכל עשוהו לבדך, you cannot all by yourself listen to the problems of all the leaders and subsequently to all the problems of the individuals who feel they need your personal attention, believing that no one but you can deal with their specific problems.
(1) נבל תבל, the word is similar to the word נבלה in Genesis 11,7 when G’d announced the confounding of man’s languages, using the words ונבלה שם שפתם, “and confound their speech.” Yitro is telling Moses that his words will create confusion as he has to deal with so many people simultaneously so that his listeners would also become confused by what they heard. As a result, one would shout at the other. Yitro tells Moses that he cannot accomplish what he sets out to do by the method he has chosen.
(1) נבול תבול, “you will definitely become worn out;” the word is similar to ערבוב, “being confused.” Compare Genesis 11,7 Where G-d confused man’s languages. Yitro felt that Moses would confuse the litigants because each one would shout that he wanted to be heard next. As a result, he himself would become confused. This would be due to his inability to hear each person correctly.
(1) נבול תבול גם אתה גם העם הזה, “surely you will become weary, both you and this people.” The meaning of the words נבול תבול corresponds to Onkelos’ translation of מלאה תלאה, “you will become worn out, tired.” Yitro meant that it was irresponsible, forbidden even, for Moses to undergo such a strain and to make the people undergo such a strain. Many would stand in line and wait and never get around to have their problems aired before Moses. (2) A Midrashic approach (Pessikta Zutrata): The word נבול is a euphemism for the leaf of a fig which wilts. The application of the word נבול to leaves is found in Isaiah 34,4: “like a leaf withering on the vine, like shriveled fruit on a fig tree.” The repeated word גם is meant to include both Aaron and the seventy elders.
(2) גם אתה גם העם הזה, "both you and this people, etc." Yitro used the word גם twice to indicate that not only Moses whose powers were very great and close to inexhaustible would tire (seeing he had to preside over litigation daily for many hours), but also the people who would have to stand in line would find this too tiresome.
(4) הלה' תגמלו זאת עם נבל, “do you thus requite the Lord, o tiresome people?” The nation that strained themselves when accepting the Torah. The people considered having accepted the Torah as something which made them weary. The word נבל is reminiscent of what Yitro said (Exodus 18,18) נבל תבול, which Onkelos translates מילאה תלאי, “you will become very weary.” In our verse, Onkelos likewise translates עם נבל “they are a people who received the Torah.” According to this interpretation these words were meant as a compliment. [According to Rabbi Chavell, the meaning of Onkelos here is that the people welcomed the Torah by exerting themselves in intense study and performance, so that Moses did not criticize Israel with these words but complimented them.]
(2) גם אתה, “you also.” Rashi understands the word גם as including Aaron and Chur, and the seventy elders. If you were to point out that in Exodus 32,5, on the words: ויבן מזבח לפניו, “he built an altar in front of it (the golden calf),” Rashi comments that Aaron, having seen that Chur (his nephew) had been killed by the mob when he tried to interfere with their worshipping the golden calf, decided to instead build an altar and declare the following day a holiday in honour of G-d. The events related there occurred on the 17th of Tammuz in the first year of the people’s wanderings. Yitro meant that even if Aaron, Chur and the seventy elders were to assist Moses, this would not nearly be enough for governing such a large nation. We find an example of such thinking in Jeremiah 15,1, where G-d tells the prophet that even if Moses personally as well as the prophet Samuel were to intercede on behalf the people of the Kingdom of Yehudah at that time, their merits would not suffice to make Him change His mind concerning the impending doom of that kingdom. G-d mentioned Moses and Samuel who had already long ago passed on, The events recorded in the paragraph that we are dealing with here occurred the day after the Day of Atonement on the eleventh day of Tishrey, over 80 days after Chur had been killed. Nonetheless, Rashi saw fit to mention him as an example of a worthy assistant of Moses. However, in verse 23 in our chapter, Chur is not mentioned by Rashi. When Rashi understands the words: וכל העם הזה (and all this people) as applicable to Aaron, his two older sons, and the seventy elders, no mention is made of Chur. וכל העם הזה, they will also not be able to endure the long wait all day long to have their litigation dealt with.