GEMARA

(Rav Yehudah): If witnesses saw Reuven leave Shimon's house with Kelim hidden under his garment, Reuven is not believed to say that he bought them. This is only if Shimon does not normally sell his Kelim, and Reuven took Kelim that people do not normally hide, and Reuven does not normally hide Kelim. If any of these is not true, Reuven is believed.

This is only if Shimon claims that he lent to him the Kelim. He is not believed to say that Reuven stole them. This refers to Kelim normally lent or rented. He (Reuven) is believed about other Kelim (to say that he bought them).

(Rav Huna bar Avin): If Levi is holding Kelim not normally lent or rented, and they used to be Yehudah's, he is not believed to say that he bought them.

Rava allowed a man to collect a scissors (used by people who comb garments) and a Sefer of Agadata from orphans, because these were known to belong to him. (We assume that he lent them to their father.)

Bava Basra 33a: People were saying that Rava bar Sharshom was eating the Peros of orphans' land. He told Abaye that he took the land for Mashkanta from their father, who owed him also other money as well. He did not want to return the land after the Mashkanta expired, lest he need to swear (like anyone who wants to collect from orphans). Rather, he concealed the Mashkanta document, to continue eating the Peros until collecting the other loan as well. Migo that he would be believed to say that he bought the land, he would be believed to say that they owe me the money.

Abaye: You have no Migo to say that you bought it, for people know that it belongs to the orphans. Rather, you must return the land to them. When they grow up, you will claim your debt from them.

RISHONIM

Rif (Bava Metzia 70a): If Ploni deposited or lent to Levi, even without witnesses, something often lent or rented, and witnesses know that it was Ploni's, Levi is not believed to say that he bought it or took it for a security. Even if Levi died and his children claimed this, they are not believed, just like he was not believed. Rava took scissors and a Sefer from orphans, for they are normally lent and rented! This teaches that if Ploni deposited or lent to Levi with witnesses, even something not normally lent or rented, Levi is not believed to say that he later bought it. We needed R. Chanina (our text - Rav Huna) bar Avin's law only for a deposit not in front of witnesses. If Ploni holds an item normally lent or rented, and claims that he bought it, (if we know that it was David's) he is not believed. In Bava Basra (45b) we explicitly say that If witnesses saw the object deposited, even one who is not a craftsman would not get a Chazakah. Some Rabanan say that R. Chanina's law and Rava's ruling (about the orphans) refer to claiming items under the person's garment. Bava Metzia 116a refutes them. It asked, and did not answer that they discuss only items under one's garment! Rather, R. Chanina's law always applies. The Halachah follows it.

Rambam (Hilchos To'en 8:3): (If Ploni claims that Levi has his item,) Levi is believed to say that he bought it or took it for a security if it is something not normally lent or rented, such as clothing, Peros, house utensils and merchandise. Something often lent or rented, even if Levi has it and he did not borrow or rent it in front of witnesses, is in the Chazakah of its owner. E.g. if Reuven had a Kli often lent or rented, and witnesses know that it was his, and it was seen with Shimon, and Reuven claims that he lent or rented it to him, and Shimon claims that Reuven sold it or gave it to him for a gift or security, Shimon is not believed. Reuven takes his Kli and swears Heses. Even if Shimon died, Reuven takes his Kli. The Ge'onim say that he swears Heses, for we claim on behalf of orphans.

Rambam (9:5): If Shimon was holding a Kli often lent or rented and he died, Reuven (who was known to own it beforehand) takes it from the heirs without a Shevu'ah. Since their father could not claim that he bought it or took it for security, they cannot force Reuven to swear. If the heir makes a Vadai claim 'you gave or sold it to Shimon in front of me', Reuven swears Heses. Some say that Reuven swears Heses, and afterwards the heirs return the Kli. I disagree.

Rebuttal (Ra'avad): Anyone who receives must swear while holding a (Kodesh) item. Even something often lent or rented is taken only through such an oath, unless witnesses saw him hide things under his garment and he left. He is not believed to say that he bought them.

Magid Mishneh: The Rambam holds that Reuven swears Heses only when the heir has a Vadai claim. According to the Ra'avad, why does the Mishnah (which lists people who swear to collect) list only one who was burglarized? The Ge'onim connote that he swears without holding an item. Some exempt even from Heses. The Rambam's opinion is primary.

Rosh (Bava Basra 3:17): Rav Nachman enacted Shevu'as Heses for total denial of Metaltelim. Presumably, the same applies to total denial of land. We do not distinguish just because there is a Shevu'ah mid'Oraisa for partial admission of Metaltelim. Similarly, just like one must swear about Chazakah of Metaltelim, one must swear about Chazakah of land. Chazakah is in place of a document; one does not lose his land, for he cannot guard the document forever. However, he must swear. Rava bar Sharshom thought that he could avoid swearing, since Heses is only for a Vadai claim; the orphans did not have a Vadai claim. Alternatively, since he would need to swear in any case, he did not want to wait until they mature before collecting. This answer is better, for one collects from orphans only with a Shevu'ah. We claim for them whatever their father could have claimed, and make the creditor swear due to an uncertain claim.

Shach (CM 133:11): Tosfos (33a DH Migo) holds like the first answer. The Mechaber bring only Tosfos' opinion here, and both opinions in Siman 150:6! There, he collects Peros of land that is not his, so he must swear like one who collects. Here, he merely takes back his property.

POSKIM

Shulchan Aruch (CM 133:5): If Ploni is holding Metaltelim, he is believed that they are his if they are not normally lent or rented.

SMA (11): This refers to Sa'if 2 (the item was not given in front of witnesses; it is even if witnesses see that Ploni has it).

Shulchan Aruch (ibid): If they are normally lent or rented, and Levi has witnesses that they were his, and now saw that Ploni has them, if Levi says that he lent or rented them to Ploni, Ploni is not believed to say that he bought them or they are security for a loan.

Beis Yosef (DH u'Mah she'Chosav v'Ra'u): If witnesses did see that Ploni has them, Ploni would be believed through a Migo that he could have said that he returned them.

SMA (12): The Shulchan Aruch did not need to write that Ploni returns it after Levi swears Heses. One must swear Heses against any Vadai claim, even when Ploni's heirs are Vadai (below)!

Shulchan Aruch (ibid): This is even if he had them for three years.

Shach (8): R. Yonah, Mordechai and R. Yerucham all say so.

SMA (13): Chazakah does not work, for perhaps Levi forgot to whom he lent or rented it. Also, sometimes people borrow or rent for more than three years.

Gra (28): Craftsmen and sharecroppers cannot make a Chazakah (Bava Basra 42a). This discusses craftsmen holding Metaltelim (Rashbam). This is even after three years, like sharecroppers.

Shulchan Aruch (ibid): Even if Ploni died, Levi takes them from his heirs without a Shevu'ah.

Beis Yosef (DH v'Chosav): The Tur says that the Rambam says that the Ge'onim obligate Levi to swear Heses, for we claim on behalf of orphans. He missed Halachah 9:5, in which the Rambam says that he need not swear to the orphans, just like Ploni could not have made Levi swear.

Rema: The primary opinion obligates Levi to swear to receive.

SMA (14): He refers to Heses, like the Ge'onim. The Magid Mishneh refuted the Ra'avad. Also, the Ra'avad said that he swears holding an item only when Ploni is alive.

Rebuttal (Shach 9): The Darchei Moshe says that the Ra'avad holds like the Ge'onim, and they require a Shevu'ah holding an item. However, it seems that the Halachah is that one needs to swear only Heses, like the Rambam and Semag explain the Ge'onim.

Shulchan Aruch (ibid): If the heir makes a Vadai claim 'you gave or sold it to Ploni (from whom I inherited) in front of me', Levi must swear Heses.