Erchin2: 3
אֵין פּוֹחֲתִין מֵעֶשְׂרִים וְאַחַת תְּקִיעָה בַּמִּקְדָּשׁ, וְלֹא מוֹסִיפִין עַל־אַרְבָּעִים וּשְׁמֹנֶה. אֵין פּוֹחֲתִין מִשְּׁנֵי נְבָלִין, וְלֹא מוֹסִיפִין עַל־שִׁשָּׁה. אֵין פּוֹחֲתִין מִשְּׁנֵי חֲלִילִין, וְלֹא מוֹסִיפִין עַל־שְׁנֵים עָשָׂר. וּבִשְׁנֵים עָשָׂר יוֹם בַּשָּׁנָה הֶחָלִיל מַכֶּה לִפְנֵי הַמִּזְבֵּחַ: בִּשְׁחִיטַת פֶּסַח רִאשׁוֹן, וּבִשְׁחִיטַת פֶּסַח שֵׁנִי, וּבְיוֹם טוֹב רִאשׁוֹן שֶׁל־פֶּסַח, וּבְיוֹם טוֹב שֶׁל־עֲצֶרֶת, וּבִשְׁמֹנַת יְמֵי הֶחָג. וְלֹא הָיָה מַכֶּה בְּאַבּוּב שֶׁל־נְחֹשֶׁת, אֶלָּא בְּאַבּוּב שֶׁל־קָנֶה, מִפְּנֵי שֶׁקּוֹלוֹ עָרֵב. וְלֹא הָיָה מַחֲלִיק אֶלָּא בְאַבּוּב יְחִידִי, מִפְּנֵי שֶׁהוּא מַחֲלִיק יָפֶה.
We do not [blow] less than twenty-one trumpet blasts in the Temple, nor more than forty-eight. We do not [use] less than two lyres, nor more than six. We do not [use] less than two flutes, nor more than twelve. On twelve days during the year, the flute plays before the Altar: During the slaughtering of the first pesach offering, and during the slaughtering of the second pesach offering, and on the first Yom Tov of Pesach, and on the Yom Tov of Shavuos, and on the eight days of the Festival. And he would not play a copper flute, but a reed flute, because its sound is pleasant. And he would conclude with only a single flute, because it would make for a better close.