Avodah Zarah, Daf Nun Het, Part 6
ר"ל איקלע לבצרה חזא ישראל דקאכלי פירי דלא מעשרי ואסר להו
חזא מיא דסגדי להו עובדי כוכבים ושתו ישראל ואסר להו
אתא לקמיה דרבי יוחנן א"ל אדמקטורך עלך זיל הדר בצר לאו היינו בצרה ומים של רבים אין נאסרין
R. Shimon b. Lakish once came to Botzrah and saw Jews eating untithed produce and he prohibited it to them.
He saw water which had been worshipped by idolaters being drunk by Israelites and he prohibited it to them.
He came before R. Yohanan. [R. Yohanan] said to him, While your cloak is still on you, return; Betzer is not Botzrah; and water belonging to the public cannot become prohibited!
R. Shimon b. Lakish believes that the people he sees are committing two errors they are eating produce that should have been tithed, and they are drinking water that is prohibited.
R. Yohanan disagrees on both counts and sends Resh Lakish back to Botzrah to let the people know that he had erred in his ruling. First of all, Botzrah is not Betzer. Betzer is mentioned in Deuteronomy 4:43 and is part of Israel. Since it s not part of Israel, the people there do not need to tithe. Second, the water is not prohibited. The Talmud will now explain why.
רבי יוחנן לטעמיה דא"ר יוחנן משום ר"ש בן יהוצדק מים של רבים אין נאסרין
R. Yohanan here followed his own opinion, for R. Yohanan said in the name of R. Shimon b. Yehotzadak: Water belonging to the public cannot become prohibited.
According to R. Yohanan, water belonging to the public cannot become prohibited, even if people worship it.
הא דיחיד נאסרין
ותיפוק ליה דהא מחוברין נינהו
לא צריכא דתלשינהו גלא
But if it belongs to an individual it does become prohibited.
But it should be excluded for the reason that it is something attached to the ground!
No; it is necessary [to mention it because it can be prohibited in the case] where a wave detached it from the ground.
By deduction, if water owned by the public cannot become prohibited, water owned by an individual can. The problem is that in general things attached to the ground cannot become prohibited. Water is considered attached to the ground and thus should not become prohibited.
The Talmud answers that if a wave detached the water, and then people worshiped it, it can become prohibited.
סוף סוף אבני הר שנדלדלו נינהו תסתיים דר’ יוחנן דאמר אסורות לא צריכא דטפחינהו בידיה
In any case [such water may be compared] to boulders which had broken away [from a mountain]; and it must therefore be concluded that it was R. Yohanan who said they were prohibited!
No; it is necessary [to suppose a case] where [a non-Jew] struck [the waters] with his own hand.
Earlier, on daf 46 there was a discussion about boulders that had become detached from a mountain on their own force, without human intervention. Can such boulders become prohibited if worshiped? Water that becomes detached by a wave is similar a natural feature that becomes detached from its source on its own. So if R. Yohanan holds that it is prohibited, he must be the one who held that boulders detached from the ground are prohibited.
The Talmud again refines the case the water worshiped here was not detached simply by a wave. Rather, a non-Jew struck the water, then worshiped the detached water. Can a Jew now use such water? R. Yohanan would say yes, but this does not mean that he is the one that holds that the boulders are permitted.