A person must speak in the language of his teacher
A person must attribute words or teachings to their original source and not present them as their own. One should give due credit to the original speaker or teacher.
("Hillel says: A full hin of drawn water invalidates the ritual bath, but a person must speak in the language of his teacher. Shammai says: nine kabim, and the sages say: not like this nor like that." – Eduyot 1:3)
Translation
Expression (Hebrew)
אָדָם חַיָּב לוֹמַר בִּלְשׁוֹן רַבּוֹ
Definition (Hebrew)
חַיָּב אָדָם לוֹמַר דְּבָרִים בְּשֵׁם אוֹמְרָם וְלֹא לְהַצִּיגָם כְּאִלּוּ הֵם שֶׁלּוֹ. צָרִיךְ לָתֵת אֶת הַכָּבוֹד לַדּוֹבֵר הַמְּקוֹרִי שֶׁל הַדְּבָרִים.
("הִלֵּל אוֹמֵר: מְלֹא הִין מַיִם שְׁאוּבִין פּוֹסְלִין הַמִּקְרֶה, אֶלָּא שֶׁאָדָם חַיָּב לוֹמַר בִּלְשׁוֹן רַבּוֹ. וְשַׁמַּאי אוֹמֵר: תִּשְׁעָה קַבִּין, וַחֲכָמִין אוֹמְרִים: לֹא כְּדִבְרֵי זֶה וְלֹא כְּדִבְרֵי זֶה" - עֵדוּיוֹת א ג)