תָּנוּ רַבָּנַן: מַעֲשֶׂה בְּגוֹי אֶחָד שֶׁבָּא לִפְנֵי שַׁמַּאי. אָמַר לוֹ: כַּמָּה תּוֹרוֹת יֵשׁ לָכֶם? אָמַר לוֹ: שְׁתַּיִם, תּוֹרָה שֶׁבִּכְתָב וְתוֹרָה שֶׁבְּעַל פֶּה. אָמַר לוֹ: שֶׁבִּכְתָב אֲנִי מַאֲמִינְךָ, וְשֶׁבְּעַל פֶּה — אֵינִי מַאֲמִינְךָ. גַּיְּירֵנִי עַל מְנָת שֶׁתְּלַמְּדֵנִי תּוֹרָה שֶׁבִּכְתָב. גָּעַר בּוֹ וְהוֹצִיאוֹ בִּנְזִיפָה. בָּא לִפְנֵי הִלֵּל, גַּיְירֵיהּ. יוֹמָא קַמָּא אֲמַר לֵיהּ: א״ב ג״ד. לִמְחַר אֲפֵיךְ לֵיהּ. אֲמַר לֵיהּ: וְהָא אֶתְמוֹל לָא אֲמַרְתְּ לִי הָכִי! אֲמַר לֵיהּ: לָאו עֲלַי דִּידִי קָא סָמְכַתְּ? דְּעַל פֶּה נָמֵי סְמוֹךְ עֲלַי.
The Sages taught: There was an incident involving one gentile who came before Shammai. The gentile said to Shammai: How many Torahs do you have? He said to him: Two, the Written Torah and the Oral Torah. The gentile said to him: With regard to the Written Torah, I believe you, but with regard to the Oral Torah, I do not believe you. Convert me on condition that you will teach me only the Written Torah. Shammai scolded him and cast him out with reprimand. The same gentile came before Hillel, who converted him and began teaching him Torah. On the first day, he showed him the letters of the alphabet and said to him: Alef, bet, gimmel, dalet. The next day he reversed the order of the letters and told him that an alef is a tav and so on. The convert said to him: But yesterday you did not tell me that. Hillel said to him: You see that it is impossible to learn what is written without relying on an oral tradition. Didn’t you rely on me? Therefore, you should also rely on me with regard to the matter of the Oral Torah, and accept the interpretations that it contains.