Sanhedrin 20B

סירוגו מתוכו, מטה ⁠– סירוגה מעל גבה.

has its weaving on its inside, in that the straps woven to hold the bedding are tied in holes inside the bed posts, while a bed has its weaving on its outside, in that its straps are tied around the posts.

מיתיבי: כלי עץ, מאימתי מקבלין טומאה? המטה והעריסה ⁠– משישופם בעור הדג. ואי מטה מסורגת היא מעל גבה, למה לי שיפת עור הדג? אלא, הא והא מתוכו: מטה ⁠– אעולי ואפוקי בבזיוני, דרגש ⁠– אעולי ואפוקי באבקתא.

The Talmud raises an objection from the Mishnah (Kelim 16:1): From when are wooden vessels considered complete and susceptible to impurity? In the case of a bed or a crib, this happens once they are rubbed with fish skin, which smoothens the wood. The Talmud asks: And if a bed is woven on its back side, as R' Yoḥanan claimed, why do I need rubbing with fish skin? Doesn’t the weaving cover the smooth part of the bed? Rather, instead of R' Yoḥanan’s explanation, say that the weaving of both this and that, a dargash and a bed, is on its inside, and the difference between them is that on a bed, the straps go in and out of holes on the posts, whereas on a dargash, they go in and out of loops.

אמר רבי יעקב: אמר רבי יהושע בן לוי: הלכה כרבן שמעון בן גמליאל. אמר רבי יעקב בר אמי: מטה שנקליטיה יוצאין ⁠– זוקפה, ודיו.

R' Ya’akov says that R' Yehoshua ben Levi says: The halakha is in accordance with the opinion of Rabban Shimon ben Gamliel that a mourner is not required to overturn a dargash, but only to untie the straps around its posts to let it fall on its own. In connection with this matter R' Ya’akov bar Ami says: In the case of a bed whose posts [naklitim] on which the canopy is spread extend, meaning that they are very long, so that the bed will remain high off the ground even if it is overturned, the mourner stands it up in the time of mourning and that is sufficient.