אֶלָּא חֲמִשָּׁה עָשָׂר בְּאָב מַאי הִיא? אָמַר רַב יְהוּדָה אָמַר שְׁמוּאֵל: יוֹם שֶׁהוּתְּרוּ שְׁבָטִים לָבוֹא זֶה בָּזֶה.
However, what is the special joy of the fifteenth of Av? Rav Yehuda said that Shmuel said: This was the day on which the members of different tribes were permitted to enter one another’s tribe, by intermarriage. It was initially prohibited to intermarry between tribes, so as to keep each plot of land within the portion of the tribe that originally inherited it. This halakha was instituted by the Torah in the wake of a complaint by the relatives of the daughters of Zelophehad, who were worried that if these women married men from other tribes, the inheritance of Zelophehad would be lost from his tribe (see Numbers 36:1–12).
אָמַר רַב מְנַשְּׁיָא: וְקָרוּ לֵיהּ יוֹם תְּבַר מַגָּל. מִכָּאן וְאֵילָךְ, דְּמוֹסֵיף — יוֹסֵיף, וּדְלָא מוֹסֵיף — יֵאָסֵף. מַאי ״יֵאָסֵף״? אָמַר רַב יוֹסֵף: תִּקְבְּרֵיהּ אִימֵּיהּ.
Rav Menashya said: And they called the fifteenth of Av the day of the breaking of the scythe, as from this date onward no more trees were cut down, and therefore it was a celebration for the trees. The Gemara adds: From the fifteenth of Av onward, when the days begin to shorten, one who adds to his nightly Torah study will add years to his life, and he who does not add [mosif] will be gathered [ye’asef]. The Gemara asks: What is the meaning of the phrase: He will be gathered? Rav Yosef said: It means that his mother will bury him, as he will be gathered to his grave (see Genesis 49:33).
שֶׁבָּהֶן בְּנוֹת יְרוּשָׁלַיִם כּוּ׳. תָּנוּ רַבָּנַן: בַּת מֶלֶךְ שׁוֹאֶלֶת מִבַּת כֹּהֵן גָּדוֹל, בַּת כֹּהֵן גָּדוֹל —מִבַּת סְגָן, וּבַת סְגָן — מִבַּת מְשׁוּחַ מִלְחָמָה, וּבַת מְשׁוּחַ מִלְחָמָה — מִבַּת כֹּהֵן הֶדְיוֹט, וְכׇל יִשְׂרָאֵל שׁוֹאֲלִין זֶה מִזֶּה כְּדֵי שֶׁלֹּא (יִתְבַּיֵּישׁ) [לְבַיֵּישׁ] אֶת מִי שֶׁאֵין לוֹ.
§ The mishna taught: As on them the daughters of Jerusalem would go out in white clothes, and on the fifteenth of Av they would go out to the vineyards and dance. The Sages taught this tradition in greater detail: The daughter of the king borrows white garments from the daughter of the High Priest; the daughter of the High Priest borrows from the daughter of the deputy High Priest; the daughter of the deputy High Priest borrows from the daughter of the priest anointed for war, i.e., the priest who would read verses of Torah and address the army as they prepared for battle; the daughter of the priest anointed for war borrows from the daughter of a common priest; and all the Jewish people borrow from each other. Why would they all borrow garments? They did this so as not to embarrass one who did not have her own white garments.
אָמַר עוּלָּא בִּירָאָה, אָמַר רַבִּי אֶלְעָזָר: עָתִיד הַקָּדוֹשׁ בָּרוּךְ הוּא לַעֲשׂוֹת מָחוֹל לְצַדִּיקִים, וְהוּא יוֹשֵׁב בֵּינֵיהֶם בְּגַן עֵדֶן, וְכׇל אֶחָד וְאֶחָד מַרְאֶה בְּאֶצְבָּעוֹ, שֶׁנֶּאֱמַר: ״וָאֹמַר בַּיּוֹם הַהוּא הִנֵּה אֱלֹהֵינוּ זֶה קִוִּינוּ לוֹ וְיוֹשִׁיעֵנוּ זֶה יהוה קִוִּינוּ לוֹ נָגִילָה וְנִשְׂמְחָה בִּישׁוּעָתוֹ״.
Ulla Beirah said that Rabbi Elazar said, "In the future the Holy One, blessed be He, will make a dance for the righteous ones, and He will sit among them in the Garden of Eden, And each and every one points [to God] with his finger, as it is stated (Isaiah 25:9), 'And it shall be said on that day, "Behold, this is our God, for Him have we waited, that He might save us; this is the Lord, for whom we waited; we will be glad and rejoice in His salvation."’"