Shimon Ha’amsoni (others say it was Nechemia Ha’amsoni) was explaining the significance of each and every time the word “et” appears in the Torah. However, when he reached the verse “et Hashem Elokecha tira” (Deut. 6:13) — fear the L-rd your G-d — he stopped. His students said to him, “Our Rabbi, what will become of your explanations of the word “et” that you taught until now?” He replied, “Just as I received reward for explaining, so too I will receive reward for abstaining from explaining.” Then Rabbi Akiva came and taught that the word “et” in the verse “et Hashem Elokecha tira” teaches to include Torah scholars (i.e., just as the verse teaches the mitzvah to fear G-d, likewise it teaches to fear Torah scholars).
This beraita on our daf is based on the idea that every word and letter in the Torah has meaning. Therefore, even the word “et”, which does not have any particular translation, must be there to include something else that is not mentioned explicitly each time it appears in the Torah. This is why these Sages sought to explain what each “et” in the Torah is meant to teach. Shimon Ha’amsoni “did not know” what to do with the “et” in this verse (Rashi).
The Maharsha on our daf refers to Rashi’s commentary in Masechet Kiddushin (57a), where Rashi writes that the Sage “feared” to equate the fear of “anything else” to the fear of G-d, and could therefore not attribute any meaning to the word “et” in the verse that appears in the command to fear G-d. Based on this explanation, the Maharsha explains why this Sage said that he would receive reward for ceasing to explain the meaning of each “et” in the Torah, just as he had received reward for toiling in Torah study to attempt attributing special meaning to this word in other cases. His act of “cease and desist” when encountering the word “et” in the verse commanding fear of G-d was itself a true act of awe and fear of G-d, and therefore deserving of the reward for fulfilling this mitzvah to fear G-d.
Tosefot asks a question on the stance of the Sage Shimon Ha’Amsoni. “Why did he cease?” asks Tosefot, who cites a gemara (Kiddusin 30b) which in fact equates the fear of one’s parents to the fear of G-d. Why didn’t he continue to interpret “etim” in the Torah, and include the fear of one’s parents from the “et” in this verse? Tosefot answers that the Sage did not want to include the fear of one’s parents from the “et” in this verse since he did not want to derive from here a second, additional mitzvah to fear one’s parents from the existence of this word in this verse. Which begs the question: “Why not?” I once suggested the following explanation of the answer of Tosefot to a great Rabbi in Jerusalem: If the Sage would derive from the word “et” in this context that there are actually two positive commands to fear one’s parents, as opposed to “only” one positive mitzvah to fear G-d, doing so would be an act of “lack of fear of G-d” — and contrary to the mitzvah stated explicitly in the verse.
(As a parenthetic remark, it appears that Tosefot understands Shimon Ha’Amsoni’s reason for stopping differently than Rashi does, as explained by the Maharsha. According to Rashi he ceased since “fear of G-d” inherently means that there is no other entity to be equated to G-d, and therefore to be feared to the same degree. If so, even the fear of one’s parents would not “equate”, and would not be a “candidate” to learn from the word “et” in the mitzvah to fear G-d, and Tosefot’s question would not pose any difficulty to Rashi’s explanation (and the gemara in Kiddushin 30b could be reconciled with this approach in a number of ways). But since Tosefot asks the question regarding fearing one’s parents, Tosefot appears to understand that the Sage ceased to interpret “etim” “only” because he could not find anything suitable to include, and therefore Tosefot asks, “Why not include from this “et” fear of one’s parents?”)
Unlike the first Sage in our beraita, Rabbi Akiva felt it correct to explain that the word “et” in this verse teaches to include fear of Torah scholars as well as fear of G-d, since fearing Torah scholars is also showing honor to G-d and His Torah, because Torah scholars dedicate their lives to the study of G-d’s Torah. (Maharsha)