Reference for Sanhedrin 3:6
כֵּיצַד בּוֹדְקִים אֶת הָעֵדִים, הָיוּ מַכְנִיסִין אוֹתָן וּמְאַיְּמִין עֲלֵיהֶן וּמוֹצִיאִין אֶת כָּל הָאָדָם לַחוּץ, וּמְשַׁיְּרִין אֶת הַגָּדוֹל שֶׁבָּהֶן, וְאוֹמְרִים לוֹ אֱמֹר הֵיאַךְ אַתָּה יוֹדֵעַ שֶׁזֶּה חַיָּב לָזֶה. אִם אָמַר, הוּא אָמַר לִי שֶׁאֲנִי חַיָּב לוֹ, אִישׁ פְּלוֹנִי אָמַר לִי שֶׁהוּא חַיָּב לוֹ, לֹא אָמַר כְּלוּם, עַד שֶׁיֹּאמַר, בְּפָנֵינוּ הוֹדָה לוֹ שֶׁהוּא חַיָּב לוֹ מָאתַיִם זוּז. וְאַחַר כָּךְ מַכְנִיסִין אֶת הַשֵּׁנִי וּבוֹדְקִים אוֹתוֹ. אִם נִמְצְאוּ דִבְרֵיהֶם מְכֻוָּנִים, נוֹשְׂאִין וְנוֹתְנִין בַּדָּבָר. שְׁנַיִם אוֹמְרִים זַכַּאי, וְאֶחָד אוֹמֵר חַיָּב, זַכַּאי. שְׁנַיִם אוֹמְרִים חַיָּב, וְאֶחָד אוֹמֵר זַכַּאי, חַיָּב. אֶחָד אוֹמֵר זַכַּאי, וְאֶחָד אוֹמֵר חַיָּב, וַאֲפִלּוּ שְׁנַיִם מְזַכִּין אוֹ שְׁנַיִם מְחַיְּבִין וְאֶחָד אוֹמֵר אֵינִי יוֹדֵעַ, יוֹסִיפוּ הַדַּיָּנִין:
How are the witnesses examined (to ascertain that they are telling the truth)? They would bring them in and intimidate them. [They would apprise them that the hirers of false witnesses themselves scorn them and call them wicked, viz., in respect to Navoth (I Kings 21:10): "And seat two worthless people opposite him, and let them testify (falsely)," the king's counselors themselves, who counseled hiring them, calling them "worthless."] And they would take everyone out and leave the senior (witness) there, and they would say to him: "How do you know that this one owed that one?" If he said: "He (the borrower) told me that he owes him," "That man told me that he owes him," he has said nothing. [for people are wont to say that they owe in order not to be thought rich.] (He is not accepted as a witness) until he says: "Before us he admitted to him that he owes him two hundred zuz." [i.e., Both of them were before us and his intent was to acknowledge the debt and have them witness the acknowledgement.] Then the second one is brought in and he is examined. If their stories jibe, they (beth-din) deliberate. If two say "Not liable," and one says "Liable," he (the borrower) is not liable. If two say "Liable," and one "Not liable," he is liable. If one says "Not liable," and one says "Liable" — and even if two say "Not liable" or two say "Liable," and one says "I do not know" — they add judges. [And even though if he had differed with the others, he, being in the minority, would be overruled, when he says "I do not know," it is as if he had not sat in judgment, so it is as if the judgment were with two, and we require three.]