Chagigah 17A

רב אשי אמר: אפילו תימא צדדין מותרין, כל דבהדי גבה ⁠— כגבה דמי.

Rav Ashi said: Even if you say that sides are permitted in general, there is no proof from here, since anything that is near the animal’s back is considered as its back. Therefore, placing the hands on the head of the animal is the same as placing them on the animal itself, as opposed to its sides.

מתני׳ בית שמאי אומרים: מביאין שלמים, ואין סומכין עליהם, אבל לא עולות. ובית הלל אומרים: מביאין שלמים ועולות, וסומכין עליהם.

Mishnah: Beit Shammai say: One may bring peace-offerings on a Festival because both the owners and the priests partake of them, but one may not place his hands on them, on the peace-offerings before sacrificing them. However, one may not bring burnt-offerings at all because they are not eaten, and labor is permitted on Festivals only for the sake of preparing food for humans. And Beit Hillel say: One may bring peace-offerings and also burnt-offerings, and one places his hands on both of them.

עצרת שחל להיות בערב שבת, בית שמאי אומרים: יום טבוח אחר השבת. ובית הלל אומרים: אין יום טבוח אחר השבת. ומודים שאם חלה להיות בשבת, שיום טבוח אחר השבת.

If the festival of Shavuot occurs on Friday, Beit Shammai say: The day of slaughter is after Shabbat, on Sunday. This is the day on which the animals brought in honor of the pilgrim Festival are slaughtered, since they maintain that the Festival burnt-offering is not sacrificed on the Festival day itself but on the following day, and all burnt-offerings vowed by individuals are postponed to the following day. And Beit Hillel say: The day of slaughter is not after Shabbat. Since the slaughter may be performed on the Festival day itself, it is unnecessary to postpone it. But they concede that if Shavuot occurs on Shabbat, the day of slaughter is after Shabbat.