ACQUISITION OF A METZI'AH
(Mishnah): Reuven and Shimon are holding a garment. Reuven says 'I found it', and so does Shimon; Reuven says 'it is mine', and so does Shimon. Each swears that he does not own less than half, and they divide it.
If Reuven says 'it is all mine' and Shimon says 'it is half mine', Reuven swears that he does not own less than three quarters, and Shimon swears that he does not own less than one quarter. Each gets like he swore.
If two men are riding on an animal, or one is riding and the other is leading it, and each says 'it is mine', each swears that he does not own less than half, and they divide it.
When they admit, or when they have witnesses, they divide without an oath.
(Gemara) Question: Why must the Mishnah say 'Reuven says 'I found it', and so does Shimon; Reuven says 'it is mine', and so does Shimon'? It suffices for each to make one claim!
Answer #1: Indeed, each makes one claim. Each says 'I found it, and it is mine.'
Question: It should suffice to teach 'I found it.' We would know that he claims 'it is mine'!
Answer: Had it taught only 'I found it', one might have thought that this means 'I saw it', and he acquires through seeing alone. Therefore, it teaches 'it is mine' to teach that one does not acquire through seeing alone.
Question: One could not have thought that 'I found it' means that he merely saw it!
(Ravnai): "And you will find it" connotes that it came to your hand.
Answer: Indeed, in the Torah "and you will find it" connotes that it came to your hand. The Tana speaks like people do;
People say 'I found it' once they see it.
Question: It should suffice to teach 'it is mine'!
Answer: The Tana wanted to teach that one does not acquire through seeing alone;
He teaches 'I found it' and additionally 'it is mine' to teach that mere finding (seeing) does not acquire.
ARGUING ABOUT A SALE
Objection (to Answer #1): We cannot learn to say that each makes one claim. The Mishnah says 'Reuven says 'I found it' and Shimon says 'I found it'. Reuven says 'It is mine'...!'
Answer #2 (Rav Papa): The Mishnah teaches two cases. 'I found it' refers to an argument about a Metzi'ah. 'It is mine' refers to an argument about who bought an item.
It needed to teach both cases:
Had it taught only about a Metzi'ah, one might have thought that only there Chachamim imposed an oath on them, because one justifies (to himself) grabbing a Metzi'ah and claiming it (in order to receive half), since the other person did not toil for it;
Had it taught only about a purchase, one might have thought that only there Chachamim imposed an oath on them, because one justifies claiming what was sold to another person;
He reasons 'we both paid for it. I need it, so I will take it. He can get his money back and buy another.'
Question: Why must they swear about a purchase? Surely, it was sold to the one who paid!
Answer: The case is, the seller received money from both of them. He took from one willingly, and the other forced the money into his hand. We do not know from whom he accepted willingly.
LIKE WHOM IS THE MISHNAH?
(If Reuven told Shimon to pay Reuven's workers, Shimon says that he paid, and the workers deny this, Reuven must pay Shimon and the workers - Shevu'os 48a.)
Suggestion: Our Mishnah is not like Ben Nanas, for (in the above case) he says that we do not tell both parties (Shimon and the workers) to swear, for surely one of the oaths would be false. (In our Mishnah, both swear even though one of them is a false oath!)
Rejection: Our Mishnah can be like Ben Nanas. He said only there that both do not swear, for both oaths cannot be true;
Here, perhaps both oaths are true! If they picked it up at the same time, each acquired half!
Suggestion: Our Mishnah is not like Sumchus, for he holds that when in doubt about money, we divide it without an oath.
Question: It is not like Chachamim, either! They say that one cannot take money from another without proof!
Answer: It can be like Chachamim. They require a proof only to take from one who holds it (or has a Chazakah on it) by himself;
Here, both are holding it, so they swear and divide it.
Sumchus holds that even when one person holds it, they divide it without swearing. All the more so when both are holding it, they divide it without swearing!
Rejection: Our Mishnah can even be like Sumchus. He said that they divide it without swearing only when both parties are unsure. Here both parties make definite claims, so they swear and divide it.
Question: Rabah holds that Sumchus says that they divide without swearing even when both make definite claims. Can he establish the Mishnah like Sumchus?
Answer #1: Yes. Sumchus said that they divide it without swearing only when there is Drara of money. Here, there is no Drara. (Rashi - Drara is a loss of money. Not acquiring a Metzi'ah is not considered a loss. Tosfos - Drara is when even without their claims, Beis Din had a doubt. Here, the doubt is due to their claims. Ramban - it is a claim based on an undisputed Chazakah.)