R. Gamliel wanted to establish the practice of Demai (that one who buys from an Am ha'Aretz must be concerned lest he did not separate Ma'aseros) in Surya, and R. Hoshayah did not let him;

R. Hoshayah: If [you enact] so, Kohanim will be concerned for their Chalah (that it is Tevel to Ma'aseros)!

Question: R. Hoshayah contradicts himself! There, he said (Demai does not apply to Chalah, because) 'fear of Kodshim is on him, and [an Am ha'Aretz] does not give to the Kohen something that is not fixed (tithed)', and here he says so (Kohanim will be concerned for their Chalah)?!

Answer #1 (R. Mana): [R. Hoshayah said that fear of Kodshim is on an Am ha'Aretz] here in Eretz Yisrael (that tithes are mid'Oraisa). Here, in Chutz la'Aretz (i.e. Surya, he says that Kohanim will be concerned. We explained this like SEFER NIR)

Answer #2 (R. Bun bar Chiyah): I say that he gave to him [the Chalah] for fire (since it is not eaten, perhaps the Am ha'Aretz was not careful to tithe it).

One who buys from a baker, or from a woman who makes in order to sell in the market, he must separate Chalas Demai. [One who buys from] a Ba'al ha'Bayis (who made for himself), or a guest (eating from a Ba'al ha'Bayis) need not separate Chalas Demai.

(R. Yonah citing R. Chananyah, the colleague of Rabanan): This is a guest [who eats from] his (the Ba'al ha'Bayis') dough (but not if he bought from a baker).

(R. Yonah): [The Ba'al ha'Bayis is trusted] only if they saw him knead by someone (he gave the flour to someone else to bake it. The other has no reason not to separate Chalah. If the Ba'al ha'Bayis bakes for himself, perhaps he is stingy and does not want to separate Chalah. We explained this like MEICHAL HA'MAYIM.)

(Tosefta): The Chazakah of Ba'alei Batei Yisrael in Surya, one need not separate Demai on them. If it is known that most of the Peros are his, they are obligated.

Question (R. Bun bar Chiyah): Does this not argue with R. Hoshayah (who did not allow R. Gamliel to enact Demai in Surya)?!

Answer (R. Mana): R. Hoshayah taught only about their Chalah (Demai applies to it, i.e. one must separate himself, lest the seller did not separate. We must say that he holds that grain of Chutz la'Aretz that came to Surya is exempt. If not, why is it different when we know that they are his own Peros? We explained this like SEFER NIR.)