וְכִֽי־תָבֹ֨אוּ מִלְחָמָ֜ה בְּאַרְצְכֶ֗ם עַל־הַצַּר֙ הַצֹּרֵ֣ר אֶתְכֶ֔ם וַהֲרֵעֹתֶ֖ם בַּחֲצֹצְר֑וֹת וֲנִזְכַּרְתֶּ֗ם לִפְנֵי֙ יְהוָ֣ה אֱלֹֽהֵיכֶ֔ם וְנוֹשַׁעְתֶּ֖ם מֵאֹיְבֵיכֶֽם׃
你們在自己的地上出去與欺壓你們的敵人打仗時，要用這兩支號吹出斷續的號聲，你們就必在永恆者你們的上帝面前蒙記念，也必從仇敵手中得救。
Mishnah Rosh Hashanah
On [public] fast days they used shofars of rams, curved, the mouths of which were covered with silver, and there were two trumpets in between them. A short blast was made with the shofars and a long one with the trumpets, because the mitzvah of the day is with trumpets.