הַטוֹעֵן אֶת חֲבֵרוֹ בְּמִטַּלְטְלִין וְהוֹדָה לוֹ בְּמִקְצָת הֲרֵי זֶה מְשַׁלֵּם מַה שֶּׁהוֹדָה בּוֹ וְנִשְׁבָּע עַל הַשְּׁאָר מִן הַתּוֹרָה שֶׁנֶּאֱמַר (שמות כב ח) "אֲשֶׁר יֹאמַר כִּי הוּא זֶה". וְכֵן אִם כָּפַר בַּכּל וְאוֹמֵר לֹא הָיוּ דְּבָרִים מֵעוֹלָם וְעֵד אֶחָד מֵעִיד [שֶׁהוּא חַיָּב לוֹ] הֲרֵי זֶה נִשְׁבָּע מִן הַתּוֹרָה. ומִפִּי הַשְּׁמוּעָה לָמְדוּ שֶׁכָּל מָקוֹם שֶׁשְּׁנַיִם מְחַיְּבִין אוֹתוֹ מָמוֹן אֶחָד מְחַיְּבוֹ שְׁבוּעָה. וְכֵן לָמְדוּ מִפִּי הַשְּׁמוּעָה שֶׁעֵד אֶחָד לְכָל עָוֹן וּלְכָל חַטָּאת אֵינוֹ קָם אֲבָל קָם הוּא לִשְׁבוּעָה:
When a person who issues a claim against a colleague with regard to movable property, and the defendant acknowledges a portion of the claim, he must pay what he acknowledged, and take an oath with regard to the remainder. This is a Scriptural obligation, as Exodus 22:8 states: "That this is it." Similarly, if the defendant denies the entire obligation and says: "Such a thing never happened," and one witness testifies that the defendant is obligated to the plaintiff, the defendant is obligated by Scriptural Law to take an oath. The Oral Tradition teaches: Whenever two witnesses would obligate the person to pay money, one witness obligates him to take an oath. Similarly, it was derived through the Oral Tradition that one witness shall not rise up against any man for any iniquity or any sin. He may, however, rise up against him to obligate him to take an oath.
