Explanation: The argument of the Mishnah and Beraisa does not pertain to the argument of Abaye and Rava. Abaye, who obligates a proof, agrees that we are not concerned for Nefilah or deposit when they have the same names, like it says in Yevamos (116a);

Abaye said "we are not concerned for Nefilah. If [you will say that we should be concerned for] a deposit, since they have the same names, he would not deposit with him.

However, this Beraisa is concerned for Nefilah or deposit of Yosef ben Shimon. Even regarding two Yosef ben Shimon's, it requires a proof;

Rava said that he need not bring a proof. Above (77a) I explained. (Rabah bar Avuha collected with documents with common names. Rava inferred that we are not concerned for two "Yitzchak"s, for if we were concerned, he could not collect, lest the other Yitzchak handed over the document to him; documents are not acquired through Mesirah. Abaye disagrees. There is no concern, because Mesirah acquires documents. Neither is concerned for Nefilah or deposit.)

Implied question: In Bava Metzi'a (20b), we establish this when [the lender] found the document among his documents that were paid!

Answer: That is unlike Abaye, for he establishes it when the borrower has the receipt, like normal receipts. Rather, it is like R. Yirmeyah.

Implied question: When he has one document against them he cannot claim against them, for we are concerned for each one, lest the other wrote it, even though one of them surely borrowed. (We should likewise invalidate the receipt regarding each, for perhaps the other wrote it!)

Answer: Here we do not say about each that perhaps the other wrote and signed it, even though surely one paid, because amidst Safek we do not extract money.

Implied question: The same applies if both are Yisraelim!

Answer: Because above it taught "if one was a Kohen", it taught Kohanim.

Explanation (Kesav Yad of R. Tam): The Mishnah is abbreviated. It means as follows .If one lent to his friend through an Arev, he may not collect from the Arev.

This is the explanation, and the Halachah follows this. He may not claim from the Arev first, even though the borrower has no known property, i.e. land. Rather, he claims first from the borrower. If he was far, he waits for him [to come], or he goes to there to claim from him and force him;

We do not take the Arev's property, for perhaps if the borrower were here, he would give Metaltelim to the lender.

If [the lender had] said "on condition that I will collect first from whom I want...", he need not wait and pursue [to collect from] the borrower. Because perhaps [the borrower] would pay Metaltelim, we do not burden the lender, since he stipulated;

The case is, the borrower has no property, i.e. land, like we conclude - "what is the case?..." However, if the borrower has property, i.e. land, the lender claims first from him and forces him, and we do not burden the Arev, since the matter is revealed that he can collect from the borrower;

However, if the borrower has no property, and [the lender had] stipulated "I will collect from whom I want...", due to Safek we do not force him to pursue and wait for the borrower. Rather, he collects from the Arev, like I explained.

A Kablan, even though [the borrower] has property... (the lender may collect first from the Kablan).

Summation: There are five laws of Arvus:

If one lends through an Arev and did not stipulate "I will collect from whom I want...", he claims first from the borrower in Beis Din, whether or not the borrower has property;

If he cannot force the borrower, and he does not comply with Beis Din, he enters the Arev's house.

If he stipulated "I will collect from whom I want...", and the borrower has no property, i.e. land, he collects from the Arev first;

Explanation: This is if he wants to go to Din with the Arev first. If he wants, he may claim from the borrower first, like we said 'if he said "I will collect from whom I want...", he collects from the Arev first.' This shows that it depends on the lender's desire.

If the borrower has property, even if he stipulated, he collects first from the borrower.

A Kablan, i.e. "give to him and I will give to you" (174a), whether or not the borrower has property, he collects first from the Kablan.

If [the lender] gave to the hand [of the Arev], he collects from the Arev, and not from the borrower. The lender has no claim against the borrower. If he cannot find anything to collect from the Arev, he pursues the borrower due to R. Nasan's law (Pesachim 31a. If Levi owes David and David owes Moshe, we take from Levi to pay Moshe);

We hold like [R. Nasan] even regarding a regular creditor (who had no connection to the one who owes to the one who owes him). All the more so here [that the creditor gave money for the sake of borrower, he should be able to collect from him].

Pesak: All Arevim require a Kinyan, except for a Kablan or an Arev at the time that the money was given (176b);

A Kablan is [one who says] "give to him and I will give to you." Alternatively, he does not mention an expression of a loan, rather, an expression of payment, i.e. he says "Yeiti Dunrai" (I will give to you), and he does not say "Yeiti Divrai" (I will pay you), for the Halachah follows Rava (174a).

And he should not say "[give to him,] I am a Kablan." (Maharshal - Tosfos holds that this does not make him a Kablan, unlike the Rashbam.)

Pesak (cont.): We acquire with the buyer's Kli (Bava Metzi'a 47a-b), e.g. [the seller] holds three by three [fingers] of it. Less than this does not help if it is not a [full] Kli.

There is no distinction between leather and Sak (even though they have different Shi'urim for Tum'ah), like we say in Bava Metzi'a (7a) "once he held three by three." This is from R. Tam.

Pesak (Ri): If it was written in a document that Ploni ben Almoni is a Kablan, he is Kablan, even though it is not written in it "give to him, and I will give to you", i.e. he did not specify how he said. In any case, he said that he is a Kablan.