Beitzah 32A

הוא דאמר כי האי תנא, דתניא: חותמות שבקרקע ⁠— מתיר, אבל לא מפקיע ולא חותך, אחד שבת ואחד יום טוב. ושבכלי ⁠— בשבת מתיר, אבל לא מפקיע ולא חותך, ביום טוב ⁠— מתיר ומפקיע וחותך.

The Talmud responds: It was he, Shmuel, who spoke in accordance with the opinion of that tanna, as it is taught in a baraita: With regard to fastenings that are to the ground, e.g., those on doors, one may untie them but not unravel or cut them, both on Shabbat and on a Festival. And with regard to those fastenings of a vessel, on Shabbat one may untie them, but one may not unravel or cut them; on a Festival one may untie, or unravel, or cut them.

תרצת לך רישא, אלא סיפא קשיא!

The Talmud challenges further: You have thereby answered the first clause of Shmuel’s statement, with regard to fastenings attached to the ground, e.g., those on doors, by finding a tanna who permits untying them, as does Shmuel. However, the latter clause is difficult because the baraita states that one may not unravel even ropes of vessels on Shabbat, whereas Shmuel permits unraveling in all cases.

הא מני ⁠— רבי נחמיה היא, דאמר: כל הכלים אין ניטלין אלא דרך תשמישן.

The Talmud answers: In accordance with whose opinion is this baraita? It is in accordance with the opinion of R' Neḥemya, whose opinion is a minority view, as he said: All vessels may be handled only in the manner of their designated use. Therefore, the rope may not be cut, not because it is prohibited to unravel it but because one may not handle a knife for this purpose, as the designated use of the knife is cutting food rather than rope.

אי רבי נחמיה, מאי איריא שבת? אפילו יום טוב נמי! וכי תימא שניא ליה לרבי נחמיה בין שבות שבת לשבות יום טוב, ומי שניא ליה?

The Talmud challenges: If it is in accordance with the opinion of R' Neḥemya, why discuss particularly Shabbat? The same halakha should apply even on a Festival, as there is no distinction between Shabbat and Festivals with regard to the halakhot of handling items. And if you say that there is a distinction according to R' Neḥemya between a rabbinic decree of Shabbat, when a vessel may be moved only for its designated purpose, and a rabbinic decree of a Festival, when it may not be moved for any purpose, there is a problem. Does he differentiate between them in this manner?