Bava Batra 30A

דאמר ליה לחבריה: כל נכסי דבי בר סיסין ⁠– מזבינא לך. הואי ההיא ארעא דהוה מיקרי ״דבי בר סיסין״. אמר ליה: הא לאו דבי בר סיסין היא, ואיקרויי הוא דמיקריא ״דבי בר סיסין״. אתו לקמיה דרב נחמן, אוקמא בידא דלוקח. אמר ליה רבא: דינא הכי?! המוציא מחבירו עליו הראיה!

who said to another: I am hereby selling to you all of the property that I own of the house of bar Sisin. There was a certain parcel of land that was called: Of the house of bar Sisin. The seller said to the buyer: This parcel of land that I own is not actually of the house of bar Sisin, and it is merely called: Of the house of bar Sisin, and it is not included in the sale. They came before Rav Naḥman for judgment, and he established the land in the possession of the buyer. Rava said to Rav Naḥman: Is this the halakha? Isn’t the halakha that the burden of proof rests upon the claimant, and the land should remain in the possession of the seller?

קשיא דרבא אדרבא, קשיא דרב נחמן אדרב נחמן.

The Talmud continues: There is a difficulty from one statement of Rava to another statement of Rava, and there is also a difficulty from one statement of Rav Naḥman to another statement of Rav Naḥman, as in the first case, where the claimant states that he had been in a distant location, Rav Naḥman ruled in favor of the claimant, and Rava ruled in favor of the possessor; while in the second case, that of the property of bar Sisin, their opinions were reversed.

דרבא אדרבא לא קשיא ⁠– התם מוכר קאי בנכסיה, הכא לוקח קאי בניכסיה.

The Talmud answers: The contradiction between one statement of Rava and another statement of Rava is not difficult, because there, in the case of the property of bar Sisin, the seller had been established as having the land in his property, which is why Rava rules in his favor. But here, in the case where the claimant states that he had been in a distant location, the buyer is established as having the house in his property.