Commentary for Eduyot 1:8
כַּרְשִׁינֵי תְרוּמָה, בֵּית שַׁמַּאי אוֹמְרִים, שׁוֹרִין וְשָׁפִין בְּטָהֳרָה, וּמַאֲכִילִין בְּטֻמְאָה. בֵּית הִלֵּל אוֹמְרִים, שׁוֹרִין בְּטָהֳרָה, וְשָׁפִין וּמַאֲכִילִין בְּטֻמְאָה. שַׁמַּאי אוֹמֵר, יֵאָכְלוּ צָרִיד. רַבִּי עֲקִיבָא אוֹמֵר, כָּל מַעֲשֵׂיהֶם בְּטֻמְאָה:
Karshinim (vetch) of terumah — [In Arabic they are called "karshena." They are camel feed, and are used for human consumption only in a famine year. Terumah is separated from them, since men sometimes eat them, when forced to do so. And they are not sanctified, as other terumoth are] — Beth Shammai say: They are soaked [in water] and rubbed [on one's skin] in cleanliness [i.e., after cleansing one's hands, (netilath yadayim), according to the din of all other terumah food. For hands have the status of second-degree uncleanliness, and invalidate terumah]; and they are fed [to animals] in uncleanliness, [there being no concern about his making them unclean with his hands when feeding them to animals. But when they are not fed to animals, it is forbidden to render them unclean by the hands.] Beth Hillel say: They are soaked, in cleanliness, [for soaking them in water renders them susceptible to acquiring uncleanliness; and if he soaks them in uncleanliness, their tumah and their susceptibility come together. And this alone is what Beth Hillel forbid, as a sign, so that it be known that they are terumah], and they are rubbed (on the skin) and fed (to animals) in uncleanliness. Shammai says: Let them be eaten tzarid, ["dry," as in "tzarid of menachoth," there being a place in the meal-offerings where the oil did not reach. Here, too, let them be eaten dry, so there not be liquid upon them when they are eaten, so that it not be recognized that they were made susceptible of acquiring uncleanliness.] R. Akiva says: All that is done with them [even soaking] may be done in uncleanliness. [The halachah is in accordance with Beth Hillel.]
Bartenura on Mishnah Eduyot
English Explanation of Mishnah Eduyot
And Beth Hillel says: “They must be soaked in purity, but can be rubbed and given for food in impurity.”
Shammai says: “They must be eaten dry.”
Rabbi Akiva says: “All actions in connection with them [can be carried out] in impurity.”
In order to understand this mishnah we must first explain several rules.
1) Terumah (heave offering) is a portion of produce separated to give to the priests. It is only given from human food and not from animal feed. Vetches, a type of bean, are generally given to animals, but can be eaten by humans in time of need.
2) It is forbidden to cause terumah to become impure. A person who touches terumah must have previously ritually washed his hands.
3) Food can receive impurity only once it has been made wet. While it is dry it cannot receive impurity.
Our mishnah discusses the preparation of vetches of terumah. According to Beth Shammai they must be prepared (both soaked and rubbed) with pure hands, lest the person decide to eat them himself, in which case it would be forbidden to make them impure. However, they may be given to animals by a person with impure hands, since animal food is not really terumah.
According to Beth Hillel, they must be soaked by a person with pure hands, since getting them wet enables them to receive impurity. However, when he rubs them or gives them to an animal it is obvious that they are not intended for humans, and therefore he can do so with impure hands.
Shammai himself is again, stricter than Beth Shammai. He holds that vetches must be eaten dry so that they will not be able to receive impurity. Assumedly, Shammai would agree that a person might also eat them with clean hands.
Rabbi Akiva’s opinion is the most lenient. He holds that vetches are not fit for human consumption and therefore one may do anything with them while his hands are impure. Since vetches are animal food the rules of the purity of terumah do not apply to them.