More Torah on one foot TB Shabbat 93

I concluded yesterday’s daf TB Shabbat 92 by citing Rambam’s pesak. Moses Maimonides codifies in the Mishneh Torah, Sefer Zemanim, Hilchot Shabbat Chapter 1, Halacha 15 that a prohibited labor that can be done by one person, but is done by two people they are exempt, פטור, from bringing a sin offering. Today’s daf TB Shabbat asked the question what is the law if one person can do it by himself and another person joins him in partnership?  Rav Hisda decides that the person who is capable of performing the prohibitive labor all by himself is liable while the second person who is participating is exempt because he is not necessary.

“We learned earlier that the Master said: In a case where this person is capable, and this person is incapable, and they performed it together, everyone agrees that he is liable. The Gemara seeks to clarify: Which of them is liable? Rav Ḥisda said: The one who is capable of performing the act alone is liable, as if it was the one who is incapable of performing the act alone that was liable, what is he doing that would render him liable? His efforts are inadequate to perform the task. Rav Hamnuna said to Rav Ḥisda: He is doing quite a bit, as he is assisting him. He said to him: The assistance provided by one who assists another to perform a task that the other could have performed himself is insubstantial,                מְסַיֵיעַ אֵן בּוֹ מַמָשׁ.” (Sefaria.org translation)

The Gemara gives four different proofs that assistance provided to perform a task, מְסַיֵיעַ, which the first person could perform by himself, is insubstantial and exempt. I’ll just share one of the four proofs. When a priest offered up a sacrifice he could not wear shoes for nothing could come between his feet and the floor of the Temple. Secondly, his feet had to be on the floor of the Temple. If the priest could offer up the sacrifice balancing himself on one foot we learn that the other foot is an assist, מְסַיֵיעַ, and not necessary; consequently the sacrifice like that is valid.

“Rav Ashi said: We, too, also learned support for this halakha in a different mishna. Rabbi Eliezer says: With regard to a priest that stood in the Temple, and one of his feet was on a vessel, and one of his feet was on the floor, or one of his feet was on a stone, and one of his feet was on the floor, while performing priestly Temple rites; we see, if the vessel was removed or the stone was removed, whether he would still be capable of standing on one foot on the ground. If so, his service is valid. And if he could not stand on one foot, his service is invalid. Is he considered to be standing on the floor, in which case the service is valid, or is he not considered to be standing on the floor, in which case the service is invalid? The Gemara asks: And why, if he would still be capable of standing on one foot, should it be valid? Don’t his legs assist each other? Isn’t the reason because we say: One who assists is insubstantial?” (Sefaria.org translation)

Moses Maimonides codifies in the Mishneh Torah, Sefer Zemanim, Hilchot Shabbat Chapter 1, Halacha 16 according to Rav Hisda. If one person can do the prohibitive labor all by himself and another assist him only the person who can do the prohibitive labor all by himself is obligated to bring a sin offering, חייב.