(Rav Nachman): If Reuven and Shimon each claimed 'I inherited this land (or ship) from my fathers', Kol d'Alim Gavar.

Question: Why is this different than two documents with the same date (for the same field, but one gives it to Levi, and the other gives it to Yehudah)?

(Rav): Levi and Yehudah split the property. (Rav holds like R. Meir, who says that signatures empower a document. Even if one was given first, the signatures of both take effect at the same moment, the end of the day (the date on the document). Alternatively, he holds like R. Elazar, who says that the witnesses who saw a document handed over empower it. The first to receive his document acquired the property. We do not know which was first, and neither is Muchzak, so they divide it.)

(Shmuel): The judges use their discretion (Rashbam - whom the giver liked more; Tosfos - to whom the judges prefer to give it).

Answer: There, we will never know which document was given first. Here, perhaps one will bring witnesses later! (We do not want to give a ruling that might be overturned later).

Question: Why is this (Rav Nachman's law) different than the following?

(Mishnah): Levi traded his cow for Shimon's donkey, or sold his slave to Shimon, and the cow or slave gave birth. (The mother was not in front of us at the time of the sale.) Levi claims that the birth was before the trade or sale (so the child was not included), and Shimon claims it was after, and he acquired a pregnant mother (so the child is his). They divide the value of the child.

Answer: There, each has Drara of money (Rashbam - grounds to suspect that it is his, for he owned the mother at some point; Tosfos - Beis Din would have a doubt even without their claims);

Here, it belongs to one, and the other is simply lying.

(Chachamim of Neharde'a): If a third person grabbed the contested property, he keeps it.

(R. Chiya - Beraisa): One who steals from many people (fighting over the property) is not considered a thief.

Rejection (Rav Ashi): No, he is a thief. (Since he has no claim to it, we take it from him);

R. Chiya meant that one who steals from many people cannot (simply) return the theft. (He is Yotzei only if the real owner gets it back. Likewise, one who used false measures when selling does not know all the people from whom he stole.)

(Mishnah): The Chazakah is three years, from day to day.

Version #1 - Rashbam - (R. Aba): If the original owner (Reuven) helped the Machazik (Shimon) carry Peros from the land, Shimon has a Chazakah immediately.

Version #2 - R. Chananel - (R. Aba): If Shimon (the Machazik) gave Reuven a gift of Peros of the land, Shimon has a Chazakah immediately. (end of Version #2)

(Rav Zvid): If Reuven claimed that Shimon was renting the field, Reuven is believed.

This is within three years. After this, Reuven is not believed.

Question (Rav Ashi): What could Reuven have done to prevent Shimon's Chazakah (after three years) if he really was renting it?

Answer (Rav Kahana): He should have made a Macha'ah (told people that Shimon is only renting it) before three years passed (from the beginning, or from the last Macha'ah. Had Shimon truly bought it, he would know to continue to guard his document carefully.)

Support: If we would not say so, why did Chachamim sanction Mashkanta of Sura?

(There, the lender deducts a fixed amount from the loan for each year that he eats the Peros.) They write, 'At the end of these (allotted) years, the land reverts to Ploni (the borrower) for free.'

If the lender will hide the document after three years, he will be believed to say that he bought it - Chachamim would not sanction the Mashkanta if it can lead to theft!

We must say that the borrower must make a Macha'ah within (every) three years. (If he does not, he caused his own loss.)

Also here, Reuven should make a Macha'ah within (every) three years.