A very interesting take. Even if this passage was not original to the gospel it still is one of the most memorable.
A memorable lesson indeed.
Devarim ch 19
טו לֹא-יָקוּם עֵד אֶחָד בְּאִישׁ, לְכָל-עָוֺן וּלְכָל-חַטָּאת, בְּכָל-חֵטְא, אֲשֶׁר יֶחֱטָא: עַל-פִּי שְׁנֵי עֵדִים, אוֹ עַל-פִּי שְׁלֹשָׁה-עֵדִים--יָקוּם דָּבָר.
15 One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sinneth; at the mouth of two witnesses, or at the mouth of three witnesses, shall a matter be established.טז כִּי-יָקוּם עֵד-חָמָס, בְּאִישׁ, לַעֲנוֹת בּוֹ, סָרָה.
16 If an unrighteous witness rise up against any man to bear perverted witness against him;יז וְעָמְדוּ שְׁנֵי-הָאֲנָשִׁים אֲשֶׁר-לָהֶם הָרִיב, לִפְנֵי יְהוָה, לִפְנֵי הַכֹּהֲנִים וְהַשֹּׁפְטִים, אֲשֶׁר יִהְיוּ בַּיָּמִים הָהֵם.
17 then both the men, between whom the controversy is, shall stand before the LORD, before the priests and the judges that shall be in those days.יח וְדָרְשׁוּ הַשֹּׁפְטִים, הֵיטֵב; וְהִנֵּה עֵד-שֶׁקֶר הָעֵד, שֶׁקֶר עָנָה בְאָחִיו.
18 And the judges shall inquire diligently; and, behold, if the witness be a false witness, and hath testified falsely against his brother;יט וַעֲשִׂיתֶם לוֹ, כַּאֲשֶׁר זָמַם לַעֲשׂוֹת לְאָחִיו; וּבִעַרְתָּ הָרָע, מִקִּרְבֶּךָ.
19 then shall ye do unto him, as he had purposed to do unto his brother; so shalt thou put away the evil from the midst of thee.כ וְהַנִּשְׁאָרִים, יִשְׁמְעוּ וְיִרָאוּ; וְלֹא-יֹסִפוּ לַעֲשׂוֹת עוֹד, כַּדָּבָר הָרָע הַזֶּה--בְּקִרְבֶּךָ.
20 And those that remain shall hear, and fear, and shall henceforth commit no more any such evil in the midst of thee.כא וְלֹא תָחוֹס, עֵינֶךָ: נֶפֶשׁ בְּנֶפֶשׁ, עַיִן בְּעַיִן שֵׁן בְּשֵׁן, יָד בְּיָד, רֶגֶל בְּרָגֶל. {ס}
21 And thine eye shall not pity: life for life, eye for eye, tooth for tooth, hand for hand, foot for foot.