Numbers 10:2-4

Revised Standard Version

² “Make two silver trumpets; of hammered work you shall make them; and you shall use them for summoning the congregation, and for breaking camp. ³ And when both are blown, all the congregation shall gather themselves to you at the entrance of the tent of meeting. ⁴ But if they blow only one, then the leaders, the heads of the tribes of Israel, shall gather themselves to you.