4רְאוּבֵן שֶׁמָּכַר פָּרָה אוֹ טַלִּית לְשִׁמְעוֹן וּבָא יְהוּדָה לְעַרְעֵר וּלְהוֹצִיא מִיַּד שִׁמְעוֹן. רְאוּבֵן מֵעִיד לוֹ עָלֶיהָ שֶׁהִיא שֶׁל שִׁמְעוֹן שֶׁאֲפִלּוּ עָמְדָה בְּיַד שִׁמְעוֹן אֵין בַּעַל חוֹבוֹ שֶׁל רְאוּבֵן טוֹרֵף מִן הַמִּטַּלְטְלִין וַאֲפִלּוּ הָיוּ אַפּוֹתֵיקֵי. בַּמֶּה דְּבָרִים אֲמוּרִים כְּשֶׁהָיָה שִׁמְעוֹן מוֹדֶה שֶׁזּוֹ הַפָּרָה וְהַטַּלִּית הֵם שֶׁל רְאוּבֵן הַמּוֹכֵר בְּוַדַּאי וְהוּא יוֹדֵעַ שֶׁבֶּאֱמֶת הֵן שֶׁלּוֹ. אֲבָל אִם לֹא הוֹדָה שִׁמְעוֹן אֵין רְאוּבֵן מֵעִיד לְאַבֵּד זְכוּת יְהוּדָה. שֶׁאִם תֵּצֵא מִתַּחַת יְדֵי שִׁמְעוֹן יַחְזֹר שִׁמְעוֹן וְיִתְבַּע דָּמִים וְיֹאמַר לוֹ מָכַרְתָּ לִי דָּבָר שֶׁאֵינוֹ שֶׁלְּךָ שֶׁהֲרֵי בָּאוּ עֵדִים וְאָמְרוּ שֶׁהֵן שֶׁל יְהוּדָה. בַּמֶּה דְּבָרִים אֲמוּרִים שֶׁיָּעִיד רְאוּבֵן לְאַבֵּד זְכוּת יְהוּדָה וְיַעֲמִיד הַמִּטַּלְטְלִין בְּיַד שִׁמְעוֹן כְּשֶׁבָּאוּ עֵדִים וְהֵעִידוּ שֶׁהֵם יוֹדְעִים שֶׁרְאוּבֵן זֶה לֹא הָיְתָה לוֹ קַרְקַע מֵעוֹלָם. אֲבָל אִם לֹא בָּאוּ עֵדִים לְכָךְ אַף עַל הַפָּרָה וְהַטַּלִּית אֵינוֹ מֵעִיד. וְלָמָּה אֵינוֹ מֵעִיד עֲלֵיהֶן. שֶׁמָּא הִקְנָה אוֹתָם לְבַעַל חוֹבוֹ אַגַּב קַרְקַע וְכָתַב דְּאִיקְנֵי וְהִקְנָה לוֹ מִטַּלְטְלִין אַגַּב קַרְקַע שֶׁנִּמְצָא בַּעַל חוֹבוֹ טוֹרֵף אַף הַפָּרָה וְהַטַּלִּית. לְפִיכָךְ לֹא יָעִיד עֲלֵיהֶן שֶׁהֲרֵי רוֹצֶה לְהַעֲמִידָן בְּיַד שִׁמְעוֹן כְּדֵי שֶׁיָּבוֹא בַּעַל חוֹבוֹ וְיִטְרְפֵם. וְכֵן כָּל כַּיּוֹצֵא בִּדְבָרִים אֵלּוּ. וּדְבָרִים אֵלּוּ אֵינָן תְּלוּיִין אֶלָּא בְּדַעַת הַדַּיָּן וְעֹצֶם בִּינָתוֹ שֶׁיָּבִין עִקַּר הַמִּשְׁפָּטִים וְיֵדַע דָּבָר הַגּוֹרֵם לְדָבָר אַחֵר וְיַעֲמִיק לִרְאוֹת. אִם יִמָּצֵא שֶׁיֵּשׁ לְזֶה הָעֵד צַד הֲנָאָה בְּעֵדוּת זוֹ אֲפִלּוּ בְּדֶרֶךְ רְחוֹקָה וְנִפְלָאָה הֲרֵי זֶה לֹא יָעִיד בָּהּ. וּכְדֶרֶךְ שֶׁלֹּא יָעִיד בְּדָבָר זֶה שֶׁמָּא נוֹגֵעַ בְּעֵדוּתוֹ הוּא כָּךְ לֹא יָדוּן בְּאוֹתוֹ דָּבָר. וְכֵן שְׁאָר מִינֵי פְּסוּלִין כְּשֵׁם שֶׁפּוֹסְלִין בְּעֵדִים כָּךְ פּוֹסְלִין בְּדַיָּנִים:
When, by contrast, Reuven sold a cow or a garment to Shimon and Yehudah raised a claim to expropriate it from Shimon, Reuven may testify that it belongs to Shimon. The rationale is that even if it were to remain in Shimon's possession, a creditor of Reuven does not have the right to expropriate movable property that was sold. This applies even when the movable property was designated as an apoteiki. When does the above apply? When Shimon the purchaser admits that the cow or the garment certainly belonged to Reuven the seller and he knows that they truly belonged to him. If, however, Shimon does not acknowledge this, Reuven may not testify to deny Yehudah's right to the property. For if it is expropriated from Shimon, he will sue Reuven for its value, saying: "You sold me an article that did not belong to you, for witnesses came and stated that it belonged to Yehudah." When do we accept Reuven's testimony to deny Yehudah's right to the movable property and thus leave it in Shimon's possession? When witnesses come and testify that Reuven never owned landed property. If, however, there are no witnesses to deliver such testimony, Reuven may not testify concerning a cow or a garment as well. Why may he not testify concerning such objects? Because it is possible that he placed them on lien to his creditor by virtue of the latter's lien on landed property and in that contract stated: "That I will acquire," establishing a lien on them by virtue of the lien on the landed property. Thus his creditor has the right to expropriate a cow and a garment as well. Hence, Reuven should not testify concerning them. For he desires to have them remain in Shimon's possession so that his creditor can come and expropriate them. Similar principles apply in all analogous situations. These matters are dependent solely on the discerning capacity of the judge and the greatness of his understanding when he comprehends the fundamental thrust of the judgments and knows how one thing leads to another, deepening his perception. If he sees that a witness will derive benefit from this testimony even in an uncommon and extraordinary manner, he should not allow that person to testify. Just as a person should not testify with regard to a matter because he may have a vested interest in the case; so, too, he should not act as a judge concerning such a matter. Similarly with regard to other disqualifying factors, just as they disqualifying a person as a witness; so, too, they disqualify him as a judge.