Menachos Daf 10 מנחוס דַף 10

On the previous Daf, Rebbe Zeira explained why קמיצה performed בשמאל – with the left hand is פסול: a passuk about קמיצה mentions "כפו" – his palm, and since the passuk about מצורע states the oil is poured על כף הכהן השמאלית – on the Kohen’s left palm, and the word "שמאלית" is extra, it teaches that only this "כף" refers to the left, הא כל מקום שנאמר כף אינו אלא ימין – but anywhere else that “palm” is mentioned, it means only the right one. Rava provides a different source: since the Torah states to pour the oil “on the blood of the asham” which was placed on the מצורע’s right hand and toe, why does the Torah explicitly write to pour it on the “right” hand and toe? Therefore, Rava explains: יד יד לקמיצה – the gezeirah shavah of "יד יד" teaches to require the right hand for kemitzah, רגל רגל לחליצה – the gezeirah shavah of "רגל רגל" teaches to require the right foot for chalitzah of a יבמה, and אוזן אוזן לרציעה – the gezeirah shavah of "אוזן אוזן" teaches to require the right ear for boring the ear of an עבד עברי who chooses to remain an עבד.

Rabbah bar bar Chanah said: כל מקום שנאמר אצבע וכהונה אינה אלא ימין – wherever “a finger” and Kehunah are stated in a passuk, it means none other than the right hand. This is derived from מצורע, where the passuk uses both terms and explicitly requires ימין. However, since the passuk of קמיצה only mentions Kehunah, and קמיצה with the left hand is פסול, Rava clarifies that wherever either "אצבע" or כהונה is written, it means to require ימין. Abaye asked Rava that "כהונה" is written regarding הולכת אברים לכבש – bringing the limbs [of a korban] to the ramp of the מזבח, yet some limbs of the קרבן תמיד were carried in their left hands!? Rava answered that this rule only applies to something which is מעכב the כפרה, similar to the procedure of the מצורע. Regarding קבלת הדם, where the passuk mentions כהונה, the Tanna Kamma of a Mishnah invalidates קבלה done with the left hand, but Rebbe Shimon validates it. The Gemara ultimately explains that Rebbe Shimon holds that "כהונה" does not require ימין; only "אצבע" does. Therefore, Rebbe Shimon also allows זריקה to be done with the left hand.

Having established that the word "כהונה" alone requires using the right hand, and the word "כהונה" is written regarding kemitzah, the Gemara asks why Rava’s gezeirah shavah of "יד יד" for kemitzah is necessary. It answers: חד לקומץ – one source requires using the right hand for kemitzah, וחד לקידוש קומץ – and the other one requires using the right hand for sanctifying the kometz in a כלי שרת. This answer does not suffice for Rebbe Shimon, who also has another source requiring ימין for kemitzah, because Rebbe Yannai says Rebbe Shimon does not require קידוש קומץ at all, and Rav Nachman bar Yitzchak holds that although he does require קידוש קומץ, he holds it can be done with the left hand. According to Rebbe Shimon, the Gemara explains that "יד יד" teaches that the right hand is required for kemitzah of a מנחת חוטא. Since Rebbe Shimon explained that oil and לבונה are not placed on this minchah שלא יהא קרבנו מהודר – so that his korban should not be elegant, one might have thought that its kemitzah would also be valid with the left hand, so this derashah teaches otherwise.