(Rava): The Halachah is, in its time, Chametz forbids b'Mashehu, whether b'Mino or Lo b'Mino - this is like Rav;

Not in its time it is permitted even b'Mino - this is like R. Shimon.

Question: But Rava said that R. Shimon fines [Chametz after Pesach] because one transgressed Bal Yera'eh and Bal Yimatzei!

Answer: He fines intact Chametz, not a mixture.

This is like Rava taught elsewhere:

(Rava): When we were in Rav Nachman's academy, after Pesach he would tell us to buy Chametz (Beis Yosef, cited in Gilyon ha'Shas - dough or Se'or) of Nochrim [even though it was made during Pesach - this is like R. Shimon.]

(Rav): Pots may not be Kashered for use on Pesach; they must be broken.

Question: He should allow to leave them to be used after Pesach Lo b'Mino [even if Mashehu absorptions of Chametz will enter the food, Rav permits this]!

Answer: He decrees lest one will use them b'Mino.

(Shmuel): They need not be broken - one leaves them until after Pesach, then they may be used even for b'Mino.

This is like Shmuel taught elsewhere:

Shmuel (to pot sellers): Do not raise your prices [after Pesach] - if you do, I will expound that the Halachah follows R. Shimon [that one may keep pots to use them after Pesach.

Question: [In any case] Shmuel should expound that the Halachah follows R. Shimon, since he holds like R. Shimon!

Answer: It was Rav's region.

An oven was smeared with fat; Rabah bar Ahilai forbade all bread that will ever be baked in it, even to eat it with salt, lest it be eaten with Kutach (a common dairy dip).

Question (Beraisa): We may not knead a dough with milk; if this was done, all the bread is forbidden, lest it be eaten with meat;

Similarly, we may not smear an oven with fat of the tail [and bake bread]; if this was done, all the bread is forbidden, unless the oven was Husak (heated up - this gets rid of the fat) before this.

Inference: If the oven was Husak, the bread is permitted!

Rabah is refuted.

Question (Ravina): Since Rabah was refuted, this should also refute Rav, who says that pots [may not be Kashered for Pesach, they] must be broken!

Answer #1 (Rav Ashi): Rav establishes the Beraisa to discuss a metal oven (Hesek Kashers it, but Cheres (earthenware) cannot. R. David - we do not give this answer for Rabah - it was known that he forbids even a metal oven, lest one will bake without heating it).

Answer #2: Also the Beraisa discusses an oven of Cheres - it can be Kashered, for it is Husak from the inside [where the lard is];

Rav requires breaking pots on Pesach, for they cannot be Kashered by Hesek from the outside.

Question: He should permit Kashering pots through Hesek from the inside!

Answer: We are concerned that the owner will not heat them enough, lest they break.

Corollary: Therefore, Buchya [a Keli made of tiles; bread is baked or fried in it] cannot be Kashered [if it was smeared with lard,] for it is normally heated from the outside (opposite the lard);

If one fills it with coals, this will [heat it from the inside and properly] Kasher it.

Question (Ravina): What do we do with knives on Pesach?

Answer (Rav Ashi): I make new ones.

Ravina: You can afford to - if someone cannot afford to, what can he do?

Rav Ashi: I meant, I make my knives like new - I cover the [wooden] handles in mud [so they will not burn during Koshering] and put the blade in fire, then I put the handles [without the mud] in boiling water.

The Halachah is, it suffices for the blade and handle to be in boiling water in a Keli Rishon.

(Rav Huna brei d'Rav Yehoshua): A wooden mixing spoon may be Kashered in boiling water in a Keli Rishon.

He holds that k'Bol'o Kach Polto (just like it absorbs, it emits).

Question: May Kunya (Klei Cheres plated with lead) be used on Pesach [if they had been used with Chametz]?

If they are green, they absorb, surely they are forbidden; the question is only if they are white or black;

If they have cracks, they absorb, they are forbidden; the question is only if they are smooth.

Answer (Ameimar): We see that the outer walls give off moisture - this shows that they absorb, hence they are forbidden.

[Question: Why can't they be Kashered?]

Answer: The Torah teaches that absorptions never leave the walls of Klei Cheres ("U'Chli Cheres Asher Tevushal Bo Yishaver").

Question: Why is the law of Kunya different for Chametz than for Yayin Nesech (wine used for idolatry)? Regarding Yayin Nesech, Mereimar permits, whether they are black, white or green!

Suggestion: We are more stringent regarding Chametz, for it is a mid'Oraisa prohibition, but Yayin Nesech is mid'Rabanan.

Rejection: We pattern Rabbinic decrees like mid'Oraisa laws!

Answer (Ameimar): Chametz is absorbed hot; wine is absorbed cold.

(Rava bar Aba): Any Keli used for cold Chametz may be used for Matzah, except for Beis Se'or (a Keli in which Se'or is soaked), for it (Se'or) is very potent Chametz (it is absorbed even though it is cold);

(Rav Ashi): Beis Charoses (a Keli in which Chametz is kept with sharp foods) is like Beis Se'or;

(Rava): Since dough is constantly kneaded in troughs of Mechuza (Rava's city), and is often left there, they are like Beis Se'or.

Objection: This is obvious!

Answer: Since they are wide and get much exposure to the air, one might have thought that they do not absorb - Rava teaches that this is not so.

(Mishnah): If a Nochri lent [money] to a Yisrael [relying] 'on' the Yisrael's Chametz (it was collateral), it is permitted after Pesach;

If a Yisrael lent to a Nochri 'on' the Nochri's Chametz (it was collateral), it is Asur b'Hana'ah.

(Gemara - Abaye): When a creditor collects [Meshubad property, i.e. he had a lien on it], this is retroactive [as if he collected from the time of the loan];

(Rava): He collects from now (not retroactively).