(Mishnah): If Se'or of Chulin and of Terumah fell into a dough, and there was not enough of this to ferment it [by itself] or of this to ferment it, and they joined and fermented it, R. Eliezer says, I follow the last one. (If Terumah fell in last, only Kohanim may eat the dough, in Taharah);

Chachamim say, whether the Isur fell in first or last, it is forbidden only if there was enough [Se'or of Isur] to ferment [by itself].

Yo'ezer Ish ha'Birah was a Talmid of Shamai. He said, I asked about R. Gamliel ha'Zaken standing in the eastern gate [of Har ha'Bayis], and he said always, it is forbidden only if there was enough [Isur] to ferment [by itself].

(Gemara - Mishnah): Yayin Nesech is forbidden, and forbids a mixture of any amount.

(Chizkiyah): If a cup [of water] was mixed with [wine] of Isur and Heter, and Isur fell last, it is forbidden. If Heter fell last, it is permitted.

(R. Shmuel bar Rav Yitzchak): This is like R. Li'ezer, for R. Li'ezer said, I follow the last one.

Rejection (R. Yirmeyah): (Chizkiyah can hold like Rabanan.) This is a stringency of Yayin Nesech.

Question (R. Yosi): If this is a stringency of Yayin Nesech, even if Heter fell at the end, it should be forbidden!

(R. Yosi citing R. Yochanan): A cup mixed from Isur and Heter, you view the Heter [wine] as if it is not. If the Isur is Nosen Ta'am [to the water], it is forbidden, and if not, it is permitted;

Limitation (R. Hoshayah): This is if the Heter fell last.

(R. Imi citing R. Yochanan): It makes no difference whether the Isur fell first and Heter last, or Heter first and Isur last;

Even water and wine, and even if it was mixed as much as needed from Heter (there was enough Heter wine to mix with the water to make properly diluted wine), you view the Heter as if it is not. If the Isur is Nosen Ta'am [to the water], it is forbidden, and if not, it is permitted;

Question (R. Ze'ira): This that you said that it is in all conditions (whether the Isur fell first or last), how is this? (TOLDOS YITZCHAK)

Answer (R. Yosi bei R. Bun citing R. Avahu citing R. Yochanan): If a flask of Yayin Nesech fell into a barrel of wine, and it returned and fell into a pit of water, you view the Heter as if it is not. If the Isur is Nosen Ta'am [to the water], it is forbidden, and if not, it is permitted. (The rest of the wine was never actual Isur, just before it fell into water, it was forbidden due to the Yayin Nesech mixed with it.)

Question: This [argument of R. Li'ezer and Rabanan] is when the [sourdoughs] fell one after the other. If they fell at once, what would R. Li'ezer say?

Answer: We learn from the following [Tosefta];

Question: When is Chametz of Kusim permitted after Pesach? (E.g. they began and ended Pesach early, for they hold that it must begin on Shabbos, so they made Chametz during the true Pesach, so it is forbidden, and use Se'or from it to ferment doughs afterwards - SHA'AREI TORAS ERETZ YISRAEL, based on Tosefta Pesachim 2:2.)

Answer: Of a Ba'al ha'Bayis is permitted after three Shabbosos of baking (after this, they finished their Se'or from Pesach). Of bakers in big cities, it is after three ovens in one Shabbos (they bake a large amount each time). Of bakers in villages, it is after three days;

R. Shimon ben Elazar says, even when they said that of a Ba'al ha'Bayis is after three Shabbosos of baking, this is if he is a great man (many eat at his table) or he marries off his son and baked three ovens in one Shabbos, one after the other. After this, it is permitted;

And even when they said that of bakers in villages, it is after three days, if he was pressed, and baked three ovens in one day, after the other, it is permitted.

(Beraisa - R. Shimon): And even when they said that of bakers in villages, until three ovens, it is forbidden until three days, for in the morning he takes Se'or for the entire day. (SHA'AREI TORAS ERETZ YISRAEL - bakers in big cities bake too much to do so. Rather, they take Se'or from each dough for the next dough.)

Summation of answer: The second dough [that the Kusi makes after Pesach] - is it not fermented through Isur (Se'or from Pesach) and Heter (the first dough after Pesach?! If you permit when Isur and Heter fall together, i.e. due to Zeh v'Zeh Gorem, also here, the second dough would be permitted)!

(R. Yirmeyah citing Reish Lakish): Who taught [the Tosefta of] Chametz of Kusim? It is R. Li'ezer. (However, you cannot learn from it Rabanan's opinion.)

(R. Yosi, to R. Chanina Antuniya): Do you remember that you and R. Yirmeyah used to say in the name of Reish Lakish 'who taught Chametz of Kusim? It is R. Li'ezer';

And we did not say so, rather, R. Heila said in the name of Reish Lakish [Chachamim taught it, and] they hold regarding Chametz of Kusim like R. Li'ezer!

Support: R. Chanina said in the name of R. Avahu, a case occurred in which my father sent to R. Chiya, to R. Yosi and to R. Imi, and they ruled for him like R. Li'ezer;

What, did they rule like an individual!? (Surely not!) Rather, [Chachamim] hold regarding Chametz of Kusim like R. Li'ezer.

Question (R. Mana, to R. Yosa): Just like you say there that the Halachah follows R. Li'ezer, [also] here, does the Halachah follow R. Li'ezer?

Answer (R. Yosa): For everything [does the Halachah follow R. Li'ezer?! We rule like him only regarding Chametz of Kusim, because they finish the Se'or of Pesach in the specified time - MEICHAL HA'MAYIM.]