Jerusalem Talmud Bava Metzia 8:4

משנה: הַמַּחֲלִיף פָּרָה בַחֲמוֹר וְיָֽלְדָה וְכֵן הַמּוֹכֵר שִׁפְחָתוֹ וְיָֽלְדָה זֶה אוֹמֵר עַד שֶׁלֹּא מָכַרְתִּי וְזֶה אוֹמֵר מִשֶּׁלָּקַחְתִּי יַחֲלוֹקוּ. הָיוּ לוֹ שְׁנֵי עֲבָדִים אֶחָד גָּדוֹל וְאֶחָד קָטָן וְכֵן שְׁתֵּי שָׂדוֹת אַחַת גְּדוֹלָה וְאַחַת קְטַנָּה. הַלּוֹקֵחַ אוֹמֵר הַגָּדוֹל לָקַחְתִּי וְהַמּוֹכֵר אוֹמֵר אֵינִי יוֹדֵעַ זָכָה בַגָּדוֹל. הַמּוֹכֵר אוֹמֵר הַקָּטוֹן מָכַרְתִּי וְהַלָּה אוֹמֵר אֵינִי יוֹדֵעַ אֵין לוֹ אֶלָּא קָטָן. זֶה אוֹמֵר גָּדוֹל וְזֶה אוֹמֵר קָטָן יִישָּׁבַע הַמּוֹכֵר שֶׁהַקָּטָן מָכַר. זֶה אוֹמֵר אֵינִי יוֹדֵעַ וְזֶה אוֹמֵר אֵינִי יוֹדֵעַ יַחֲלוֹקוּ. MISHNAH: Somebody exchanged a cow for a donkey and it gave birth, or he sold his slave girl and she gave birth. If one said, [it happened] before I sold, the other said, after I bought, they shall split²⁰If neither of them has proof.. If he had two slaves, one adult and one young, or two fields, one large and one small. The buyer says, I bought the large one, and the seller says, I do not know: he acquired the large one²¹Even if neither of them has proof, judgment has to be given to the one who claims certainty against one who asserts uncertainty.. The seller says, I sold the small and the other party says, I do not know: he has only the small one²¹Even if neither of them has proof, judgment has to be given to the one who claims certainty against one who asserts uncertainty.. If one says the large one and the other says the small, let the seller swear that he sold the small one²²Both assert their claim with certainty and neither of them has proof. Since the buyer did not yet enter into possession, the seller may substantiate his claim by an oath.. If both say, I do not know, they shall split²³Since neither of them asserts his claim as certain, the rule applies that “money in doubt has to be split evenly” (Chapter 1, Note 5)..

הלכה: אָמַר לוֹ הִשְׁאִילָהּ לִי כול׳. הַמַּחֲלִיף פָּרָה כול׳. אָמַר רִבִּי יוֹחָנָן. זוֹ לְהוֹצִיא מִידֵי סוּמָּכוֹס שֶׁאוֹמֵר. כָּל־הַסְּפֵיקוֹת יַחֲלוֹקוּ. אָמַר רִבִּי לָא. תִּיפְתָּר בְּשֶׁזֶּה אוֹמֵר. בָּרִיא לִי. וְזֶה אוֹמֵר. בָּרִיא לִי. רִבִּי יוֹסֵי בָּעֵי. אִם בְּשֶׁזֶּה אוֹמֵר. בָּרִיא לִי. וְזֶה אוֹמֵר. בָּרִיא לִי. עַל דָא אָמַר רִבִּי יוֹחָנָן לְהוֹצִיא מִדִּבְרֵי סוּמָּכוֹס. HALAKHAH: “If he said to him, lend me,” etc.
“Somebody exchanged a cow,” etc. Rebbi Joḥanan said, this²⁴If both parties submit their claim as certain as in the case of Bava Metzia 8:4:1" href="/Jerusalem_Talmud_Bava_Metzia.8.4.1">Note 22. contradicts Symmachos who says that in all cases of doubt one splits evenly²⁵But in cases where both claims are tentative, the rule is universally accepted and we do not need Symmachos’s statement. Cf. Babli 100a.. Rebbi La said, explain it if both of them say, I am certain²⁶He holds that Symmachos gave his rule only in cases where nobody submits a certain claim.. Rebbi Yose explained, if both of them say, I am certain, that is what Rebbi Joḥanan refered to when he said, this contradicts Symmachos’s words.