Talmud Bavli – Yevamot
Yevamot 62b
The Talmud records that 24,000 students of Rabbi Akiva died between Pesach and Shavuot because they did not treat each other with respect, and this period became one of mourning. This is the foundational source for sefira mourning practices.
רַבִּי עֲקִיבָא אוֹמֵר: לָמַד תּוֹרָה בְּיַלְדוּתוֹ — יִלְמוֹד תּוֹרָה בְּזִקְנוּתוֹ. הָיוּ לוֹ תַּלְמִידִים בְּיַלְדוּתוֹ — יִהְיוּ לוֹ תַּלְמִידִים בְּזִקְנוּתוֹ, שֶׁנֶּאֱמַר: ״בַּבֹּקֶר זְרַע אֶת זַרְעֶךָ וְגוֹ׳״. אָמְרוּ: שְׁנֵים עָשָׂר אָלֶף זוּגִים תַּלְמִידִים הָיוּ לוֹ לְרַבִּי עֲקִיבָא מִגְּבָת עַד אַנְטִיפְרַס, וְכוּלָּן מֵתוּ בְּפֶרֶק אֶחָד, מִפְּנֵי שֶׁלֹּא נָהֲגוּ כָּבוֹד זֶה לָזֶה. תָּנָא, כּוּלָּם מֵתוּ מִפֶּסַח וְעַד עֲצֶרֶת. אָמַר רַב חָמָא בַּר אַבָּא וְאִיתֵּימָא רַבִּי חִיָּיא בַּר אָבִין: כּוּלָּם מֵתוּ מִיתָה רָעָה. מַאי הִיא? אָמַר רַב נַחְמָן: אַסְכָּרָה.
Rabbi Akiva says that the verse should be understood as follows: If one studied Torah in his youth he should study more Torah in his old age; if he had students in his youth he should have additional students in his old age, as it is stated: “In the morning sow your seed, etc.” They said by way of example that Rabbi Akiva had twelve thousand pairs of students in an area of land that stretched from Gevat to Antipatris in Judea, and they all died in one period of time, because they did not treat each other with respect. With regard to the twelve thousand pairs of Rabbi Akiva’s students, the Gemara adds: It is taught that all of them died in the period from Passover until Shavuot. Rav Ḥama bar Abba said, and some say it was Rabbi Ḥiyya bar Avin: They all died a bad death. The Gemara inquires: What is it that is called a bad death? Rav Naḥman said: Diphtheria.
Why it matters — Establishes the historical and halakhic basis for the mourning period of the omer, from which all restrictions including music derive.