Eruvin 4A

שלא יהו מכוונות. בשלמא לרבא ⁠— כי היכי דליהויין הללו שוחקות והללו עצבות. אלא לאביי קשיא!

that they are not precisely a cubit. Granted, according to Rava, the baraita means: So that these, the cubits of diverse kinds of seeds, should be measured with expansive handbreadths, and those, the cubits of sukka, should be measured with depressed handbreadths. However, according to Abaye, it is difficult.

אמר לך אביי, אימא: אמת כלאים באמה בת ששה.

The Talmud answers: Abaye could have said to you: Emend the baraita and say: The cubit of diverse kinds of seeds mentioned by the rabbis is measured with a cubit of 6 handbreadths, not the other cubits.

והא מדקתני סיפא: רבן שמעון בן גמליאל אומר: כל אמות שאמרו חכמים בכלאים באמה בת ששה, ובלבד שלא יהו מצומצמות, מכלל דתנא קמא כל אמות קאמר!

The Talmud raises a difficulty. However, from the fact that it is taught in the latter clause of the baraita that Rabban Shimon ben Gamliel says: All the cubits that the rabbis mentioned with regard to diverse kinds of seeds are measured with cubits of 6 handbreadths, provided that they are not measured with exact handbreadths? This proves by inference that the anonymous first tanna is speaking of all cubits, and not only those in the case of diverse kinds of seeds.

אמר לך אביי: ולאו מי איכא רבן שמעון בן גמליאל דקאי כוותי, אנא דאמרי כרבן שמעון בן גמליאל.

The Talmud answers that Abaye could have said to you: Isn’t there Rabban Shimon ben Gamliel, who holds in accordance with my opinion? I stated my opinion in accordance with the opinion of Rabban Shimon ben Gamliel.

לאביי ודאי תנאי היא. לרבא מי לימא תנאי היא?

The Talmud comments: According to Abaye, the issue of large and small cubits is certainly subject to a dispute between tanna’im, as his ruling can only be in accordance with the opinion of Rabban Shimon ben Gamliel. According to Rava, however, must it be said that this is subject to a dispute between tanna’im?