§ The Sage Peleimu raised a dilemma before Rabbi Yehuda HaNasi: In the case of one who has two heads, on which of them does he don phylacteries? Rabbi Yehuda HaNasi said to him: Either get up and exile yourself from here or accept upon yourself excommunication for asking such a ridiculous question. In the meantime, a certain man arrived and said to Rabbi Yehuda HaNasi: A firstborn child has been born to me who has two heads. How much money must I give to the priest for the redemption of the firstborn? A certain elder came and taught him: You are obligated to give him ten sela, the requisite five for each head. בְּעָא מִינֵּיהּ פְּלֵימוֹ מֵרַבִּי: מִי שֶׁיֵּשׁ לוֹ שְׁנֵי רָאשִׁים, בְּאֵיזֶה מֵהֶן מַנִּיחַ תְּפִילִּין? אֲמַר לֵיהּ: אוֹ קוּם גְּלִי, אוֹ קַבֵּל עֲלָךְ שַׁמְתָּא. אַדְּהָכִי אֲתָא הָהוּא גַּבְרָא, אֲמַר לֵיהּ: אִיתְיְלִיד לִי יָנוֹקָא דְּאִית לֵיהּ תְּרֵי רֵישֵׁי, כַּמָּה בָּעֵינָא לְמִיתַּב לְכֹהֵן? אֲתָא הָהוּא סָבָא תְּנָא לֵיהּ: חַיָּיב לִיתֵּן לוֹ עֲשָׂרָה סְלָעִים.

— Bavli Menachot (Sida 37a:7)