Eruvin 52B

כמאן ⁠— כרב יוסף, ואליבא דרבי יוסי בר יהודה?

The Talmud comments: In accordance with whose opinion did Rav Natan bar Oshaya act? Apparently, it was in accordance with the opinion of Rav Yosef that everyone agrees that he must set out on his way, and in accordance with the opinion of R' Yosei bar Yehuda that he need not declare that he is establishing his residence at the end of his Shabbat limit.

לא, כרבה, ואליבא דרבי יהודה.

The Talmud rejects this suggestion: No, that is not necessarily so, as it is possible to say that he acted according to the opinion of Rabba, and in accordance with the opinion of R' Yehuda, and Rav Yehuda bar Ishtata declared that he establishes his residence at the end of his Shabbat limit.

רבי מאיר אומר כל שיכול לערב כו׳. הא תנינא חדא זימנא: ספק, רבי מאיר ורבי יהודה אומרים: הרי זה חמר גמל.

We learned in the Mishnah that R' Meir says: Anyone who can establish an eiruv, and negated his residence in his original place, and did not establish an eiruv, is likened to both a donkey driver and a camel driver. The Talmud asks: Didn’t we have already learned it once before in another Mishnah: In a case of uncertainty, R' Meir and R' Yehuda say: This person is likened to both a donkey driver and a camel driver. Here too, it is obvious that the same applies, as that is R' Meir’s opinion with regard to all uncertain cases.

אמר רב ששת לא תימא טעמא דרבי מאיר ספק עירב ספק לא עירב הוא דהוי חמר גמל, אבל ודאי לא עירב ⁠— לא הוי חמר גמל.

Rav Sheshet said: It is necessary to state this ruling here as well, so that you will not say the reason for R' Meir’s statement only applies in a case where there is uncertainty whether one established an eiruv or did not establish an eiruv, and in that case he is in likened to both a donkey driver and a camel driver. However, in a case where there is certainty that he did not establish an eiruv he is not likened to both a donkey driver and a camel driver, but his Shabbat limit is the same as the rest of the residents of his city.