Menachos Daf 65 מנחוס דַף 65

The next Mishnah describes the reaping of barley for the עומר. שלוחים of Beis Din tied the barley into bundles while it was attached to the ground, so it would be easier to reap. Residents of nearby towns gathered there, כדי שיהא נקצר בעסק גדול – so it should be reaped as a great affair. Once it became dark, the one reaping asked those present a series of questions, with each exchange repeated three times. He asked "בא השמש" – “Has the sun set?”, and they answered "הין" – “Yes.” He asked, "במגל זה" – “With this sickle?,” "קופה זו" – “This basket?,” and "שבת זו" – “[On] this Shabbos?,” all of which they affirmed. He asked, "אקצור" – “Shall I reap?” and they answered, "קצור" – “Reap!,” and this exchange was also repeated three times. The reason for all these questions was to publicize the date of reaping for the עומר, because the בייתוסים said it was not on the night following Yom Tov (i.e., the first day of Pesach), but on the first מוצאי שבת after Pesach.

The Baraisa of מגילת תענית enumerates days on which it is prohibited to fast, and some on which it is even prohibited to eulogize, to commemorate great events which occurred on those days. From Rosh Chodesh Nissan until the eighth day of Nissan, איתוקם תמידא – the law of the תמיד was correctly established, and even הספדים are prohibited on those days. From the eighth day until the end of Pesach, איתותב חגא דשבועיא – the correct date for the Yom Tov of Shavuos was correctly settled (as explained below), and fasting is prohibited on those days. The Gemara explains the debate about the תמיד: the צדוקים claimed that an individual can donate and bring the תמיד, because the passuk uses the singular "תעשה" – you shall make. However, the Sages countered that the next passuk about the תמיד uses the plural "תשמרו" – you shall be careful (to offer), teaching שיהיו כולן באין מתרומת הלשכה – that all [the תמידין] should come from the communal funds of the תרומת הלשכה (made from the half-shekels that all men donated annually).

The Gemara explains the debate over the date of Shavuos: the בייתוסים interpreted "ממחרת השבת" – the day after “Shabbos” to mean that the עומר was always brought on Sunday, with Shavuos occurring fifty days later. Rabban Yochanan ben Zakkai addressed them: "שוטים מנין לכם" – “Fools! From where do you know this?” An old man responded confrontationally that Moshe loved the Jews, and since Shavuos is only a single day, he fixed it to always fall out on Sunday so they should have two days of no labor. Rabban Yochanan ben Zakkai retorted that if Moshe loved the Jews, he should have brought them directly into Eretz Yisroel within eleven days, instead of taking forty years! Although the בייתוסי did not accept his response, Rabban Yochanan ben Zakkai proceeded to present the first of five proofs in this Baraisa demonstrating that ממחרת השבת refers to the second day of Pesach. Another Baraisa follows which also presents five proofs. On the next Daf, Rava says that most of them can be refuted. In the first irrefutable proof, Rebbe Yishmael compares the שתי הלחם with the עומר: just as the שתי הלחם were brought רגל ותחלת רגל – on the Yom Tov (of Shavuos), at the start of the Yom Tov, the עומר is also brought at the beginning of Pesach.