Rosh Hashanah 29A

איכוון ותקע לי. אלמא קסבר: משמיע בעי כוונה.

Have intent to sound the shofar on my behalf and sound it for me. The Talmud infers: Apparently, R' Zeira maintains that he who sounds the shofar for others is required to have intent to discharge the hearer’s obligation.

מיתיבי: היה עובר אחורי בית הכנסת, או שהיה ביתו סמוך לבית הכנסת, ושמע קול שופר או קול מגילה, אם כוון לבו ⁠— יצא, ואם לאו ⁠— לא יצא. וכי כוון לבו מאי הוי? היאך לא קא מיכוין אדעתא דידיה!

The Talmud raises an objection from the Mishnah: If one was passing behind a synagogue, or his house was adjacent to the synagogue, and he heard the sound of the shofar or the sound of the Scroll of Esther being read, if he focused his heart to fulfill his obligation, he has fulfilled his obligation, but if not, he has not fulfilled his obligation. It may be asked: And, according to R' Zeira, even if the hearer focused his heart, what of it? The other one, i.e., the one sounding the shofar, did not focus his intent to sound the shofar with him in mind? If indeed the intent of the one sounding the shofar is required, how does the passerby fulfill his obligation?

הכא בשליח ציבור עסקינן, דדעתיה אכוליה עלמא.

The Talmud answers: Here we are dealing with the representative of the community, i.e., one who sounds the shofar for the entire congregation and has everyone in mind. He does not sound it for a specific individual, but rather on behalf of the entire community, and therefore anyone who hears him sound the shofar fulfills his obligation.

תא שמע: נתכוון שומע ולא נתכוון משמיע, נתכוון משמיע ולא נתכוון שומע ⁠— לא יצא, עד שיתכוון שומע ומשמיע. קתני משמיע דומיא דשומע. מה שומע ⁠— שומע לעצמו, אף משמיע ⁠— משמיע לעצמו, וקתני לא יצא.

The Talmud raises another objection: Come and hear that which was taught in a baraita: If the hearer of the shofar had intent, but the sounder of the shofar did not have intent, or if the sounder of the shofar had intent, but the hearer did not have intent, he has not fulfilled his obligation, until both the hearer and the sounder have intent. The baraita teaches the halakha governing the sounder of the shofar in similar fashion to the halakha governing the hearer. From this it may be inferred that just as the hearer hears for himself, having intent to fulfill his own obligation, so too, the sounder sounds for himself, having intent to fulfill his own obligation, and not that of others. And the baraita teaches that if the sounder did not have this intent, the hearer has not fulfilled his obligation. But this indicates that if the sounder had intent to sound the shofar for himself, he need not have intent to sound it for others, therefore contradicting R' Zeira’s opinion.