Beitzah 31B

גמ׳ והאמרת רישא אין מבקעין כלל? אמר רב יהודה אמר שמואל: חסורי מחסרא והכי קתני: אין מבקעין מן הסואר של קורות, ולא מן הקורה שנשברה ביום טוב. אבל מבקעין מן הקורה שנשברה מערב יום טוב.

Talmud: The Talmud wonders at the wording of the Mishnah: But didn’t you say in the first clause of the Mishnah that one may not chop beams at all on a Festival, ostensibly due to the extra effort involved? Why, then, does the Mishnah later define how one may chop, and even permit the use of a cleaver? Rav Yehuda said that Shmuel said: The Mishnah is incomplete and is teaching the following: One may not chop wood from the pile of beams intended for construction, nor from a beam that broke on the Festival itself, as it is considered muktze. However, one may chop wood from a beam that broke on the eve of the Festival, since it has presumably been designated as firewood.

וכשהן מבקעין ⁠— אין מבקעין לא בקרדום ולא במגל ולא במגרה, אלא בקופיץ. תניא נמי הכי: אין מבקעין עצים לא מן הסואר של קורות ולא מן הקורה שנשברה ביום טוב, לפי שאינו מן המוכן.

Yet even when one chops such a beam, it must not be done in the weekday manner; an adjustment must be made. Therefore, one may not chop it neither with an ax, nor with a saw, nor with a sickle, but with a cleaver. The Talmud comments: This opinion, which is in accordance with the opinion of Shmuel, is also taught in a baraita: One may not chop wood, neither from the pile of beams nor from the beam that broke on the Festival itself, as it is not considered prepared.

ולא בקרדום. אמר רב חיננא בר שלמיא משמיה דרב: לא שנו אלא בנקבות שלו, אבל בזכרות שלו ⁠— מותר.

It is taught in the Mishnah that even when it is permitted to chop wood on a Festival, one may not do so with an ax. Rav Ḥinnana bar Shelemya said in the name of Rav: They taught this prohibition only with regard to a case where one chops with its female side, i.e., the broad side of the ax, as was normally done. But if one chops with its male side, i.e., the narrow side, this is permitted because it is an unusual manner of chopping.