1) HALACHAH: THIRTY DAYS FOR "PIDYON PETER CHAMOR"
QUESTION: The Gemara (end of 12b) quotes a Beraisa that states that the Mitzvah of Pidyon for a Peter Chamor must be done immediately (when the donkey is born), in contrast to the Mitzvah of Pidyon ha'Ben which is done when the baby is thirty days old. A second Beraisa, however, states that Pidyon Peter Chamor cannot be done until after thirty days have passed.
Rav Sheshes reconciles the two Beraisos. Even though the Mitzvah of Pidyon Peter Chamor takes effect immediately when the donkey is born (as the first Beraisa says), one who delays fulfilling the Mitzvah for thirty days has not transgressed. Only when he delays for more than thirty days does he transgress the Mitzvah of Pidyon Peter Chamor. (See Chart.)
If the Mitzvah of Pidyon Peter Chamor takes effect immediately when the donkey is born, then it is apparent that the Mitzvah is not comparable to the Mitzvah of Pidyon ha'Ben, since the Mitzvah of Pidyon ha'Ben takes effect only thirty days after birth. Accordingly, there is no source for Rav Sheshes' thirty-day grace period for fulfilling the Mitzvah of Pidyon Peter Chamor. The Mitzvah either should apply immediately, such that one who does not fulfill it immediately when the donkey is born transgresses the Mitzvah, or the Mitzvah should be able to be fulfilled indefinitely, and one should never transgress the Mitzvah, as is the case with the Mitzvah of Pidyon ha'Ben. What is the source for the limit of thirty days? (SHITAH MEKUBETZES #1)
ANSWER: The SHITAH MEKUBETZES answers that the thirty-day period of Rav Sheshes is mid'Rabanan. Mid'Oraisa, one does not transgress the Mitzvah until the firstborn donkey dies without Pidyon. The Rabanan instituted that one transgresses the Mitzvah when he waits more than thirty days to redeem the donkey.
HALACHAH: The SHULCHAN ARUCH (YD 321:1) rules in accordance with Rava's answer to reconcile the two Beraisos. The preferable way to fulfill the Mitzvah is to redeem the Peter Chamor immediately (as Rav Sheshes says), but it may be redeemed anytime until it dies, and one does not transgress the Mitzvah until it dies without Pidyon.
2) "IN HIS FLOCK"
QUESTION: Rebbi Oshiya is quoted as saying that when a Jew pays money to a Nochri for his animal ("bi'Vehemto"), the Jew acquires the animal immediately upon payment, through Kinyan Kesef. RASHI (DH bi'Vehemto) adds one word of explanation, "For his animal -- in his flock (b'Edro)." What is Rashi's intention with the addition of this word, "b'Edro"?
(a) The RASHASH explains that Rashi is pointing out that when the Jew gives the money to the Nochri, he is not paying for an animal that he has already taken from the Nochri. It is clear from the following words of the Gemara that in this case, the Jew has not yet performed an act of Meshichah to the animal. The money is being paid for an animal that is still in the Nochri's flock.
(b) Rashi maintains that a Jew can acquire possessions from a Nochri through a Kinyan Chatzer. Rashi's intention, therefore, is to say that the animal is not in the Jew's Chatzer (or within his four Amos), but rather it is still grazing in the Nochri's Chatzer with the rest of his flock. (See CHASAM SOFER to Avodah Zarah 71b.)
3) "KINYAN CHATZER" FOR A NOCHRI
QUESTION: Rebbi Oshiya is quoted as saying that when a Jew pays money to a Nochri to buy his animal "in accordance with their laws," the Jew acquires the animal immediately upon payment through Kinyan Kesef, even though he did no act of Meshichah, and if the animal gives birth to a firstborn calf (while still in the domain of the Nochri), the laws of Bechor apply. Similarly, when a Nochri pays money to a Jew to buy his animal "in accordance with their laws," he acquires the animal even though he did no act of Meshichah. If the animal then gives birth to a firstborn calf (while still in the domain of the Jew), the laws of Bechor do not apply, since the animal belongs to the Nochri.
Abaye explains that the phrase "in accordance with their laws" refers to the laws of Kinyanim that the Torah establishes for Nochrim. The Torah states, "Kanoh mi'Yad Amisecha" -- "[When you] acquire from the hand of your friend" (Vayikra 25:14), which teaches that Kinyan Meshichah (in which the object is drawn by the buyer "from the hand" of the seller) applies only to a transaction between two Jews ("Amisecha"). Only a Jew can effect a Kinyan with Meshichah; a Nochri effects a Kinyan with Kesef.
The Gemara asks that perhaps the verse is teaching that a Nochri is not Koneh or Makneh through any form of Kinyan. RASHI (DH Klal) explains that the Gemara is asking that until the object reaches the domain of the Jew, he does not acquire it from the Nochri. The MISHNEH L'MELECH (cited by the KEHILOS YAKOV #15, DH Bechoros) explains that it is not possible that the Gemara is suggesting that one can never acquire an object at all from a Nochri. The Torah relates that the Jewish people requested from Sichon, "Sell me food" (Devarim 2:28), which clearly implies that a Jew can acquire an object from a Nochri. Rather, when the Gemara suggests that it is not possible to acquire an object from a Nochri, it means that perhaps neither Kesef nor Meshichah are effective; the Jew acquires the object only through Kinyan Chatzer, when it enters his domain.
Similarly, when the Gemara later suggests that it is not possible for a Nochri to buy an object from a Jew, it does not mean that a Nochri cannot acquire an object at all. The Torah states that a Jew may sell a Neveilah to a Nochri (Devarim 14:21), which clearly implies that a Nochri can acquire an object from a Jew. Rather, the Gemara the means that Kinyan Kesef and Kinyan Meshichah do not work for a Nochri; it is obvious, though, that a Nochri can acquire an object through Kinyan Chatzer.
The fact that a Kinyan Chatzer is effective for a Nochri is also evident from the words of the ROSH (end of 2:2), who writes that the most preferable way to transfer the ownership of the ear of one's animal to a Nochri (in order to exempt the animal from the laws of Bechor) is to have the Nochri lease, with money, the area on which the animal is standing, so that he acquires the animal (or part thereof) through Kinyan Chatzer (see MAHARIT ALGAZI #17, DH v'Hineh ha'Rosh).
How, though, is it possible that a Kinyan Chatzer is effective for a Nochri? The Gemara in Bava Metzia (10b) quotes Reish Lakish who states that the reason why a Chatzer is able to acquire an object for the owner of the Chatzer is that it is considered like one's Shali'ach. (The ROSH to Bava Metzia (1:29) writes that this is the ruling of the RIF.) However, a Nochri cannot be appointed as a Shali'ach and cannot appoint a Shali'ach (Bava Metzia 71b). How, then, can the Nochri's Chatzer serve as a Shali'ach to be Koneh an object for the Nochri?