Shabbat 101B

אלא במים, קל הוא שהקילו חכמים במים. ואמאי, הא איכא בקיעת דגים? אלא שמע מינה ⁠— בקיעת דגים לא שמה בקיעה.

in water. It is a leniency the rabbis instituted in water but not in other circumstances. And why were they lenient with regard to a hanging partition in water? Isn’t there the passage of fish? Rather, learn from this that the passage of fish is not considered passage.

ספינות קשורות כו׳. פשיטא! אמר רבא: לא נצרכה אלא להתיר ביצית שביניהן.

We learned in the Mishnah: If boats are tied together, one may carry an object from one to the other on Shabbat. The Talmud asks: That is obvious, since these boats are like a single domain. Rava said: This Mishnah was necessary only to permit carrying from one boat to another via a small boat that is between them.

אמר ליה רב ספרא: משה, שפיר קאמרת?! ״מטלטלין מזו לזו״ תנן! אלא אמר רב ספרא: לא נצרכה אלא לערב ולטלטל מזו לזו, וכדתניא: ספינות קשורות זו בזו ⁠— מערבין ומטלטלין מזו לזו. נפסקו ⁠— נאסרו. חזרו ונקשרו, בין שוגגין ובין מזידין בין אנוסין בין מוטעין ⁠— חזרו להיתרן הראשון.

Rav Safra said to him: You, who are as great in this generation as Moses, did you speak well? We learned in the Mishnah that one may carry only from one to the other, not via a small boat. Rather, Rav Safra said: The Mishnah was only necessary to obligate one to place an eiruv, a joining of courtyards, between the two boats. Since the boats belong to different people, they must be joined to form a single domain in order to permit carrying from one to the other, as it was taught in a baraita: With regard to boats tied to one another, one places an eiruv and carries from one to the other. If the ties between them were severed, the people on the boats are prohibited to carry from one to the other. If they were then retied, whether unwittingly, i.e., the one who retied them forgot that it was Shabbat, whether intentionally, whether due to circumstances beyond one’s control, whether mistakenly, the boats are restored to their original permitted status.