(Mishnah): A Chazakah without a claim is invalid:

If Reuven said 'what are you doing in my field?', and Shimon said '(I have been here three years.) No one told me 'this is my field'', his Chazakah is invalid;

If he answered 'you (or your father) gave or sold it to me', his Chazakah is valid.

An heir does not need a claim.

(Gemara) Objection: Obviously, if Shimon has no claim why the land is his, this is not a Chazakah!

Answer: One might have thought that Shimon really bought it and lost the document;

He did not say that, for he fears lest Reuven demand to see the document. (Shimon does not know the law of Chazakah.)

One might have thought that we should ask Shimon if this is so, due to "Psach Picha l'Ilem" (speak on behalf of a mute, who cannot speak for himself)! The Mishnah teaches that we do not do so.

Rav Anan's land was flooded. The boundaries were washed away. He rebuilt the wall on his neighbor's property. Rav Nachman told him to return to the original border.

Rav Anan: I made a Chazakah!

Rav Nachman: Do you think that the Halachah follows R. Yehudah and R. Yishmael, that in front of the original owner one becomes Muchzak immediately? The Halachah is not like them!

Rav Anan: I can prove that he helped me to build the wall. (Surely, this shows that he conceded to me all the property on my side.)

Rav Nachman: He erred. He thought that it really was yours;

You yourself would not have built the wall on his side unless you erred!

Also Rav Kahana's land was flooded. He rebuilt the wall on his neighbor's property. The case came before Rav Yehudah. One witness said that he took (the width of) two rows of his neighbor's property, and the other witness said that he took three rows.

Rav Yehudah: You must return two rows.

Rav Kahana: Do you rule like R. Shimon ben Elazar?

(Beraisa - R. Shimon ben Elazar): Beis Hillel and Beis Shamai agree that if one pair of witnesses says that Reuven owes 100, and the other says that he owes 200, he must pay 100 (for all agree that he owes at least 100);

They argue when one witness says 100, and the other says 200: Beis Shamai consider this contradictory testimony (so Reuven is exempt). Beis Hillel obligate him to pay 100.

Rav Kahana: I can bring you a letter from Eretz Yisrael that the Halachah is not like R. Shimon ben Elazar! (Rather, Beis Hillel agree that Reuven is exempt.)

Rav Yehudah: Until you bring such a letter, you must return the property.

Shimon was living in the attic of Levi's house for four years.

Levi: What are you doing in my house?

Shimon: I bought it from Ploni, who bought it from you.

R. Chiya: Shimon's Chazakah is valid only if he can prove that Ploni lived there for at least one day.

Rav: Doesn't a person sometimes buy and sell the same night?

(Rav): I could see that (R. Chiya held that) if Shimon would claim that he saw Ploni buy it from Levi, he would be believed, Migo that he could have said 'I bought it from Levi''.

Support (for R. Chiya - Rava - Mishnah): An heir does not need a claim.

Inference: He does not need a claim, but he needs a proof (that the one he inherited from lived there for a day)!

Rejection #1: Perhaps he does not need a claim nor a proof!

Rejection #2: Perhaps a buyer is different, for he does not spend money for nothing. (Surely, Shimon would not have bought from Ploni unless Ploni was living there.)

Question: If people saw Ploni on the property (but not living there) for a day, what is the law?

Answer #1 (Abaye): That is just as good as living there.

Answer #2 (Rava): No. Perhaps Ploni considered buying it, but never did!

Shimon bought Reuven's field and sold it to Levi after a year. Levi sold it to Yehudah after a year. Once Yehudah has been there for a year, he has a Chazakah (because Reuven has not protested for three years).

(Rav): This is only if Shimon and Levi wrote documents of sale.

Rav holds that a document publicizes a matter, but witnesses do not.

Contradiction (Rav): If David bought Moshe's field with (only) witnesses (with Achrayus, and the field was taken by Moshe's creditor), David can collect his money from property Moshe sold after this. (We must assume that the buyers knew to beware!)