Yoma 78B

שעם ביום הכפורים? עמד רבי יצחק בר נחמני על רגליו, ואמר: אני ראיתי את רבי יהושע בן לוי שיצא בסנדל של שעם ביום הכפורים. ואמינא ליה: בתענית צבור מאי? אמר ליה: לא שנא. אמר רבה בר בר חנה: אני ראיתי את רבי אלעזר דמן ננוה שיצא בסנדל של שעם בתענית צבור, ואמינא ליה: ביום הכפורים מאי? אמר ליה: לא שנא. רב יהודה נפיק בדהיטני. אביי נפיק בדהוצי. רבא נפיק (בדיבלי). רבה בר רב הונא כריך סודרא אכרעיה ונפיק.

cork on Yom Kippur? Is it considered a shoe, and therefore it may not be worn on Yom Kippur, or not? R' Yitzḥak bar Naḥmani stood on his feet to testify and said: I saw that R' Yehoshua ben Levi went out on Yom Kippur in cork sandals, and I said to him: What is the law on a communal fast that is decreed in a time of drought, when shoes are similarly prohibited? Are reed sandals permitted? He said to me: It is no different, and such sandals are permitted even on a communal fast day. Rabba bar bar Ḥana said: I saw R' Elazar from Nineveh go out in cork sandals on a communal fast day, and I said to him: What is the law on Yom Kippur? He said to me: It is no different, and it is permitted. The Talmud reports: Rav Yehuda went out on Yom Kippur in reed sandals. Abaye went out in sandals made of palm fiber. Rava went out in sandals braided with reeds. None of these sandals are considered to be shoes. Rabba bar Rav Huna wrapped a scarf around his feet and went out.

מתיב רמי בר חמא: הקיטע יוצא בקב שלו, דברי רבי מאיר. ורבי יוסי אוסר. ותני עלה: ושוין שאסור לצאת בו ביום הכפורים. אמר אביי: התם דאית ביה כתיתין, ומשום תענוג.

Rami bar Ḥama raised an objection: We learned that an amputee may go out with his wooden prosthetic leg on Shabbat, since it is like a shoe; these are the words of R' Meir. But R' Yosei prohibits it. And a baraita was taught in that regard as an addendum to that Mishnah: And they agree that it is prohibited to go out wearing it on Yom Kippur. As this indicates that even wooden shoes are prohibited, the materials worn by the aforementioned amora’im should also be prohibited. Abaye said: There, in the case of Yom Kippur, it is prohibited because there are rags in the prosthesis. The prohibition is not due to the shoes but due to the pleasure of the comfort, which is prohibited on Yom Kippur.