Eruvin 98B

בכותל שאינו משופע, למעלה משלשה ⁠— גוללו אצלו, למטה משלשה ⁠— הופכו על הכתב.

with regard to a wall that is not inclined, the following distinction applies: If the end of the scroll is 3 handbreadths above the ground, he may roll it back to himself; but if it is below 3 handbreadths from the ground, it is considered as though the scroll is on the ground, and he must therefore turn it facedown onto the writing.

רבי יהודה אומר אפילו אינו מסולק מן הארץ וכו׳. דבעינן הנחה על גבי משהו.

It was stated in the Mishnah that R' Yehuda says: Even if the scroll is removed only a needle breadth from the ground, one rolls it back to himself. The Talmud explains: R' Yehuda maintains that in order for an object to be deemed at rest, we require that it rest atop something. Consequently, a scroll that is not actually touching the ground is not considered resting and may be rolled back.

ואלא הא דאמר רבא: תוך שלשה לרבנן צריך הנחה, לימא כתנאי אמרה לשמעתיה?!

The Talmud asks: But consider that which Rava said with regard to an object located within 3 handbreadths of the ground. Rava said that according to the opinion of the Rabbis, who disagree with R' Akiva and claim that something in the air is not considered to be at rest, nevertheless, for one to incur liability it is necessary for the object to rest on a surface. Let us say that he stated his halakha in accordance with only one of the tanna’im, but not in accordance with all of them. This is an unacceptable conclusion.

אלא: כולה רבי יהודה היא, וחסורי מיחסרא, והכי קתני: במה דברים אמורים ⁠— בכותל משופע, אבל בכותל שאינו משופע ⁠— אפילו פחות משלשה טפחים גוללו אצלו. שרבי יהודה אומר: אפילו אינו מסולק מן הארץ אלא מלא החוט ⁠— גוללו אצלו.

Rather, the Talmud rejects the previous explanation in favor of the following one: The Mishnah is all in accordance with R' Yehuda, and it is incomplete and is teaching the following: In what case is this statement that once the end of the scroll is within 10 handbreadths of the ground it may not be rolled back said? It was said in the case of an inclined wall. But with regard to a wall that is not inclined, even if the end of the scroll is less than 3 handbreadths from the ground, one may roll it back to himself, as R' Yehuda says: Even if the scroll is removed only a needle breadth from the ground, he rolls it back to himself.