Chapter 15, titled "We Are Not Experts," examines the Gemara in Kiddushin,1 which identifies the middle letter of the Sefer Torah as the vav of the word gachon2 (גחון). The Gemara records Rav Yosef's inquiry as to which half of the Torah that letter actually falls in. His colleagues propose: "Let's bring a Sefer Torah and count them. Didn't Rabbah bar bar Chanah say that they did not move from there until they brought a Sefer Torah and counted?", to which Rav Yosef responds, "אִינְהוּ בְּקִיאִי בַּחֲסֵירוֹת וִיתֵרוֹת אֲנַן לָא בְּקִיאִינַן - They were experts in the missing and extra letters. We are not experts in this regard."
Footnote 11 includes: "See Shabbos 49b and the Ben Yehoyada there."
The reference to the Ben Yehoyada was included as a subtle response to a prominent talmid chochom and rov who suggested that Rav Yosef's statement "אֲנַן לָא בְּקִיאִינַן - We are not experts in this regard" should not be taken literally as an admission of inability to verify whether the vav of gachon is indeed the middle letter. According to his interpretation, the counting is certainly possible and the midpoint of the vav of gachon is verifiable,3 but Rav Yosef simply had no interest in investing the time when it could be better spent learning Torah.
The example offered was: "Suppose someone were asked how many kal vachomers appear in the Gemara. One would likely reply, 'I don't know' - not because the answer is unknowable, but because there is no reason to count, and doing so would not constitute time well spent."
However, the Ben Yehoyada's comment on Shabbos 49b forecloses this interpretation entirely. To the contrary, the Sages were willing and eager to count every letter - notwithstanding the considerable time and effort, but it was Rav Yosef's reply that rendered the effort futile: "They were experts in the missing and extra letters. We are not experts in this regard."
For full context, the Gemara in Shabbos4records a statement of Rabbi Shimon that the word "melacha" (labor) appears in the Torah exactly 39 times. The Gemara then presents a dilemma raised by the very same Rav Yosef as in Kiddushin, and the exchange is strikingly parallel:5
בָּעֵי רַב יוֹסֵף: ״וַיָּבֹא הַבַּיְתָה לַעֲשׂוֹת מְלַאכְתּוֹ״, מִמִּנְיָנָא הוּא, אוֹ לָא? אֲמַר לֵיהּ אַבָּיֵי: וְלַיְתֵי סֵפֶר תּוֹרָה וְלִימְנֵי. מִי לָא אָמַר רַבָּה בַּר בַּר חָנָה אָמַר רַבִּי יוֹחָנָן לֹא זָזוּ מִשָּׁם עַד שֶׁהֵבִיאוּ סֵפֶר תּוֹרָה וּמְנָאוּם!
Rav Yosef asked: The pasuk says "And he [Yosef] came into the house to do his labor"6 -- is this instance [of "labor"] counted [as part of the 39 instances], or not?
Abaye said to him: Let us bring a Sefer Torah and count! Did not Rabbah bar bar Chanah say in the name of Rabbi Yochanan: They did not move from there until they brought a Sefer Torah and counted them?
The Ben Yehoyada writes the following:
מקשים למאי אצטריך להביא סיוע לדבריו מהא דאמר רבה בר בר חנה אמר רבי יוחנן הנזכר, כי לדבריו אלו שאומר 'לֵיתִי סֵפֶר תּוֹרָה וְלִמְנִי' אין צריך ראיה והוכחה?
ונראה לי בס"ד, דבלאו הכי היו אמר להם לא נביא ספר תורה ונמנה, משום ביטול בית המדרש דאיכא טרחא, וגם עובר זמן הרבה עד שיראו כל פסוקי התורה מראש ועד סוף וימנו כל מלאכה ומלאכתו הכתובים בתורה
ולכן הביא דאמר רבה בר בר חנה אמר רבי יוחנן דהביאו ספר תורה ומנו ולא חשו לביטול בית המדרש, אף על גב דבהך איכא טרחא והעברת זמן יותר למנות כל האותיות עד שיתברר האות שהוא בחצי האותיות.
The question is raised: why did Abaye need to bring proof for his position from the statement of Rabbah bar bar Chanah in the name of Rabbi Yochanan? Surely his suggestion to "bring a Torah scroll and count" requires no proof at all!
It seems to me, with Hashem's help, that without this source, people would have objected: we cannot bring a Torah scroll and count, because it would disrupt the learning in the Beis Hamedrash, involve considerable effort, and take a very long time to go through the entire Torah from start to finish and count every instance of "labor" written in the Torah.
Abaye, therefore, cited the ruling of Rabbah bar bar Chanah in the name of Rabbi Yochanan, where they actually brought a Torah scroll and counted without any concern for disrupting the study hall, even though that case also involved significant effort and actually took even longer, since they had to count every single letter until they identified the one at the exact midpoint of the Torah.