1) "BA'ALEI KISIM"
OPINIONS: Rava says that the one who maintains that grain finished by a Nochri is exempt from Terumos u'Ma'aseros also maintains that dough kneaded by a Nochri is exempt from Chalah. Rava adds that the one who maintains that grain finished by a Nochri is obligated in Terumos u'Ma'aseros also maintains that dough that was kneaded by a Nochri is obligated in Chalah. The Gemara questions Rava's statement from a Beraisa that says that grain finished by a Nochri is obligated in Terumah, while dough kneaded by a Nochri is exempt from Chalah. The Gemara answers that the Beraisa agrees that, mid'Oraisa, grain finished by a Nochri is exempt from Terumah, but it is Chayav mid'Rabanan because of a Gezeirah of "Ba'alei Kisim." To what does this Gezeirah of "Ba'alei Kisim" refer?
(a) RASHI (DH Gezeirah) explains that if the Rabanan would permit grain bought by "Ba'alei Kisim" -- wealthy people -- from Nochrim without separating, then those wealthy people might think that when they buy grain from a Jew, they also do not need to separate Terumah.
(b) In his second explanation, Rashi writes that the Gezeirah was made because of people who own a lot of property, "Ba'alei Kisim," who are stingy and do not want to separate Terumah and Ma'aser from all of their produce. Such people would give their fields to Nochrim and let the Nochrim finish the grain, effectively exempting their produce from Ma'aser.
The SHITAH MEKUBETZES questions the second explanation of Rashi. Why would the landowners give their fields to Nochrim in order to exempt their produce from Terumah and Ma'aser? It would suffice to have the Nochrim finish the harvesting of the grain, without giving possession of their fields to the Nochrim.
Perhaps Rashi rules like RABEINU GERSHOM (66b) who says that grain finished by a Nochri is exempt from Terumah and Ma'aser only when the grain is owned by the Nochri. The Shitah Mekubetzes himself maintains that even grain owned by a Jew is exempt as long as a Nochri finished the harvesting process (see previous Insight).
There seems to be a practical Halachic difference between the two explanations of Rashi. According to the first explanation, the Gezeirah applies to any grain, even grain originally owned by a Nochri. Indeed, this is the way TOSFOS (DH Gezeirah) and the RA'AVAD (Hilchos Ma'aser 11:14) apply the Gezeirah. According to the second explanation of Rashi, the Gezeirah applies only to a Jew's grain that was given to a Nochri to finish; it does not apply to grain that was always owned by a Nochri.
(c) The RAMBAM (Hilchos Terumos 4:15; see also Hilchos Bikurim 6:10) rules that grain received from a Nochri is obligated in Terumah mid'Rabanan, "a decree because of the Ba'alei Kisim; this is in order that a Jew not give his grain to a Nochri in order to exempt it from Ma'aser." However, the Rambam earlier (Hilchos Terumos 1:11-13) writes that Terumah finished by a Nochri is "completely exempt." This implies that it is not obligated even in Terumah mid'Rabanan. The KESEF MISHNEH (Hilchos Terumos 1:11) explains that the Rambam maintains that Rav Papa and Ravina argue with Rava and maintain that there is no Gezeirah of "Ba'alei Kisim."
What does the Kesef Mishneh mean? The Rambam clearly rules (in Hilchos Terumos 4:15) that there is a Gezeirah of "Ba'alei Kisim," as quoted above! Moreover, the Kesef Mishneh himself (Hilchos Terumos 4:15) explains that the Rambam rules that there is a Gezeirah of "Ba'alei Kisim"! (KEREN ORAH, MA'ASEH ROKE'ACH)
The YAD BINYAMIN explains that the Rambam maintains that the Gezeirah of "Ba'alei Kisim" was instituted only in the case of grain that the Nochri himself separated as Terumah, as indicated by the wording of the Rambam (in Hilchos Terumos 4:15). Ordinary grain bought from a Nochri (that was not separated as Terumah) was not included in the Gezeirah at all.
What, though, is the logic behind this distinction?
1. The MAHARASHDAM (YD 192) writes that the Gezeirah was made because of a problem that might arise when a Jew sees a Nochri's Terumah being sold and treated like Chulin. The Jew might think that the obligation to separate Terumah is merely to remove the Terumah from the rest of the produce, but not to treat it with Kedushah. When he sees that the Terumah separated by a Nochri is sold and treated like Chulin, he will think that any Terumah -- even Terumah separated by a Jew -- may be sold. This is why the Chachamim enacted a Gezeirah which gives a certain degree of Kedushah to the Terumah separated by a Nochri.
The Yad Binyamin has difficulty with this explanation. Why does the Gemara call this a Gezeirah because of the "Ba'alei Kisim"? Any Jew, not just "Ba'alei Kisim" who have a lot of land or who buy a lot of produce, might get confused and think that Terumah merely needs to be separated but does not need to be treated with Kedushah and given to a Kohen.
2. The Yad Binyamin therefore explains that the reason why this Gezeirah applies only to grain separated by the Nochri as Terumah is that we suspect that if a Nochri is separating Terumah in the first place, then he is probably doing so because the grain really belongs to a Jew who sold him the grain after the time of Ma'aser arrived, making the grain obligated in Ma'aser d'Rabanan (see Rambam, Hilchos Terumos 1:13). Since this grain is now suspect, the Chachamim enacted a Gezeirah of "Ba'alei Kisim" to ensure that Jews would not try to take steps to pass off their grain as Nochri-owned and exempt the grain from Ma'aser. The Yad Binyamin writes that he later found this explanation in TESHUVOS RABEINU BETZALEL ASHKENAZI (#1). (Y. MONTROSE)
2) GRAIN IN ITS HUSK
OPINIONS: Rebbi Oshiya says that if one wants to avoid the obligation to separate Ma'aser from his grain, he should bring the grain into his house when it is still in its husk so that his animal may eat it, before it becomes obligated to have Ma'aser separated from it. What is the reasoning behind this exemption?
(a) RASHI (DH b'Motz Shelah) explains that the reason for this exemption is that as long as the grain is in its husk, it is considered animal food and not food fit for human consumption. Hence, it is exempt from Ma'aser.
(b) Alternatively, Rashi explains that grain becomes obligated in Ma'aser only when it is "Ro'eh Pnei ha'Bayis" -- when it "sees the face of the house." When grain is in its husk, it does not "see" the house, since the house is hidden from the "view" of the grain, and therefore the grain does not become obligated in Ma'aser.
What is the difference between these two explanations?
1. The TZELACH in Berachos (31a) explains that according to the first explanation (that the grain is considered animal food), the grain retains its Ma'aser-free status only for as long as it remains in its husk. Once the husk comes off, the grain becomes obligated in Ma'aser. According to the second explanation, as long as the grain did not "see" the face (outside) of the house when it entered, it is exempt from Ma'aser even after its husk comes off inside the house.
The Tzelach resolves an apparent problem in Rashi's words based on this difference. In the Gemara here, Rashi gives both of these explanations. In Pesachim (9a) and Nidah (15b), however, Rashi gives only the second explanation, and he says that the Gemara is discussing a case in which the grain's husk was eventually removed. Why does Rashi here give two explanations, when it is obvious that the first explanation (that animal food is exempt from Ma'aser) is not consistent with the Sugyos in Pesachim and Nidah? The Tzelach explains that in those Sugyos, the Gemara is explaining a different opinion according to Rebbi Oshiya. That opinion can understand Rebbi Oshiya's view only according to the explanation that the grain did not "see" the face of the house. Rashi here, however, is presenting different ways to understand Rebbi Oshiya's statement, and either of these reasons are valid.
The AFIKEI YAM (2:29) takes issue with the explanation of the Tzelach. The Gemara here is also discussing a case in which the husk eventually is removed. The Gemara asks that just as there is a Gezeirah of "Ba'alei Kisim" (which makes the grain of a Nochri obligated in Terumah mid'Rabanan), there should be a Gezeirah that the Nochri's dough should be Chalah d'Rabanan because of "Ba'alei Kisim" (see previous Insight). The Gemara answers that one is able to exempt himself from the obligation to separate Chalah merely by baking less than the amount which is obligated in Chalah. The Gemara then asks that one is also able to exempt himself from Ma'aser, since one can bring his grain into his house in the manner of Rebbi Oshiya. The Afikei Yam says that this obviously means that the person can also use the grain in the normal manner, when it is outside its husk, just as he can avoid Chalah and eat normal baked goods. If the grain must remain animal food in order to be exempt, then the person cannot eat his grain in a normal manner and avoid separating Ma'aser, in which case the Gemara's question is not valid.
2. The Afikei Yam has a different understanding of Rashi's two explanations. He writes that upon closer analysis of Rashi's words in Pesachim (9a, DH v'Iy Ba'is Eima) and in Nidah (15b, DH Iba'is Eima), one finds that Rashi is saying that when the grain comes towards the house in its husk, it is considered as though it "sees" the face of the house. However, since it has not been completely processed, it cannot be called Tevel. This is the first explanation of Rashi here, and it is Rashi's preferred explanation as indicated by the fact that he gives only this explanation in the other Sugyos. Rashi understands that Rebbi Oshiya mentions the fact that its husk is still on the grain only as an indication that it has not yet been processed. Even if its husk is off, however, Rebbi Oshiya agrees that it is not obligated in Ma'aser as long as it has not been processed.
The second explanation of Rashi is similar to the explanation of the TALMID HA'RIF quoted by the SHITAH MEKUBETZES in Bava Metzia (88b). He explains that when Rebbi Oshiya says that the grain is exempt when it entered the house while still in its husk, he means that it is exempt only when it is in its husk and not when it is in any other stage before its completion. This is because only when it is covered by its husk is the grain considered not "seeing" the face of the house and, consequently, not obligated in Ma'aser after it enters the house even if its husk is subsequently removed. (See Afikei Yam there at length.) (Y. MONTROSE)