1) TAKING SOMETHING WITHOUT THE OWNER'S PERMISSION
QUESTION: The Gemara relates that seven servings of fish were placed on the table in the house of Rebbi, and five of them ended up in the possession of Rebbi Chiya while only two made it into the hands of Rebbi Shimon b'Rebbi. RASHI explains that Rebbi Chiya took five to his home without asking for permission to do so. Rebbi Shimon b'Rebbi was not upset that Rebbi Chiya took most of the fish, because he and Rebbi Chiya were friends.
TOSFOS in Bava Metzia (22a, DH Mar Zutra, cited by the SHACH CM 358:1) writes that one is not permitted to take something from another person without explicit permission, even when he knows that the other person will not object. (It is considered "Ye'ush she'Lo mi'Da'as" which does not have the status of Ye'ush.) Why, then, was Rebbi Chiya permitted to take five fish without asking for permission? (TAL TORAH)
ANSWERS:
(a) The TAL TORAH suggests that this case is not similar to a case of "Ye'ush she'Lo mi'Da'as" because the taker knows that the other person does not mind, and thus it is similar to a case of "Ye'ush mi'Da'as." When one knows that the other person does not mind, he may take the other person's belongings without asking for permission.
Accordingly, the Gemara here supports the view of the SHACH (ibid.) who argues with Tosfos in Bava Metzia (and the other Rishonim who rule like Tosfos). The Shach rules that one may take an object without permission when he knows that the owner does not mind.
(b) RASHI's words imply that Rebbi merely left the fish in a place where he normally left things for any of the Talmidim to take; he did not specifically designate the fish for Rebbi Chiya. Accordingly, Rebbi Chiya, who was one of the Talmidim, had permission to take it even though Rebbi did not give it specifically to him.

28b----------------------------------------28b

2) SHOWING A KNIFE TO A CHACHAM ON YOM TOV
OPINIONS: The Gemara says that one may not bring a Shochet's knife to a Chacham to have it inspected on Yom Tov, but a Chacham may inspect his own knife.
Why may one not show a knife to a Chacham on Yom Tov?
(a) RASHI writes that the act of bringing the knife to the Chacham has the appearance of a weekday activity ("Uvda d'Chol"). It looks as though one intends to slaughter a lot of animals for public sale.
Accordingly, a Chacham is permitted to inspect his own knife because the inspection is not done in a public manner.
(b) The RAMBAM (Hilchos Yom Tov 4:9) writes that the prohibition is due to the concern that one might sharpen the knife if the Chacham tells him that it is not perfectly sharp. A Chacham may inspect his own knife, however, because just as he is a Chacham and knows how to inspect a knife, he also knows that one is not permitted to sharpen a knife on Yom Tov.
(c) The RIF writes in the name of the BEHAG that the prohibition is due to the concern that one will carry the knife outside of his permitted Techum in order to bring it to the Chacham. For that reason, a Chacham may inspect his own knife (as he does not need to carry it anywhere).
The BA'AL HA'ME'OR asks that the reason of the Rif is logical only according to the opinion that the prohibition of Techumin is mid'Oraisa. However, according to the opinion that the prohibition of Techumin is mid'Rabanan, a prohibition against taking the knife to a Chacham would be a Gezeirah l'Gezeirah (a rabbinical decree made to safeguard another decree), which the Rabanan do not enact.
The RAMBAN (in Milchamos) answers that in this case the Rabanan made an exception to the normal rule and they enacted a Gezeirah l'Gezeirah, because it is particularly common that a person goes out of his Techum to show his knife to the Chacham, since he frequently brings his knife to the Chacham on ordinary weekdays (because one may not slaughter an animal without first giving his knife to a Chacham for inspection).
(d) The BA'AL HA'ME'OR (cited by the RAN) writes that one may not show a knife to a Chacham on Yom Tov because the Chacham's ruling about the knife is included into the category of passing judgment ("Dan Es ha'Din") which is prohibited on Yom Tov. The same reason prohibits one from showing a blemish on a Bechor to an expert on Yom Tov.
The RAMBAN asks that if the Chacham's decision about the knife is considered a judgment, then why may he inspect his own knife?
The RAN answers that when the Chacham examines his own knife, he merely clarifies ("Giluy Milsa") whether or not it has a blemish; he does not pass a formal ruling. In contrast, when another person brings a knife to the Chacham for inspection, he does so because the Rabanan instituted that one may not slaughter an animal without first showing the knife to a Chacham (this enactment was made in order to preserve the honor of the Chacham; see Rashi to Chulin 9a). Part of the enactment is that the Chacham must issue a Halachic ruling about the knife before the person may use it, and thus the Chacham's ruling is considered passing judgment. When a Chacham inspects his own knife, he does not do so because of any enactment of the Rabanan. He merely wants to clarify whether the knife is blemished or not.
3) DISCUSSING PRICES ON YOM TOV
QUESTION: The Mishnah states that a person may not ask his butcher on Yom Tov to give him a Dinar's worth of meat. Rather, the butcher must first slaughter the animal and then divide the portions. The Gemara explains that when the animal is divided, each person who wants a share of the animal must say that he wants "one portion" or "half a portion" of meat; he should not say that he wants "one Dinar's worth" or "half a Dinar's worth" of meat.
The Mishnah earlier (27b) states that the buyer and seller are not permitted to set a price for the animal on Yom Tov. Rather, the animal is slaughtered and divided, and after Yom Tov the price is set. The Gemara explains that in order to enable the price of the slaughtered animal to be assessed after Yom Tov, before the animal is slaughtered they should bring another animal of approximately the same size as the first. After Yom Tov, they assess the price of the original animal based on the value of the identical animal.
The Mishnah there (27b) teaches that the animal must be divided by the size of each portion and not by the price of each portion. What new law, then, does the Mishnah here teach?
ANSWER: The MELECHES SHLOMO answers that the previous Mishnah refers to a case in which an entire animal is being divided. In such a case, it must be divided into a half, third, quarter, etc., and it may not be divided by price. The Mishnah here, however, refers to a case in which a person wants just a single piece of meat. In such a case, he should not describe the piece that he wants as a Dinar's worth of meat, but rather as a "portion" of meat.
One might have thought that in this case he is permitted to buy a portion of meat by describing it by its price, and it is not similar to a case in which an entire animal needs to be divided (in which case dividing it by price is prohibited). In the latter case, the animal does not yet have a set price, and to establish the price on Yom Tov is prohibited. In this case, however, the individual portions have already been cut up and the prices have already been set. When one says that he wants a Dinar's worth of meat, he is not setting the price but rather he is merely describing the piece of meat in terms of its cost. The Mishnah teaches that even in such a case (when one uses the price only as a description for the meat), one should not mention the price because money should not be discussed at all on Yom Tov. (This contrasts with the explanation of the TIFERES YISRAEL who permits one to mention money.)

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