Numbers 10:2-4

King James Version

² Make thee two trumpets of silver; of a whole piece shalt thou make them: that thou mayest use them for the calling of the assembly, and for the journeying of the camps.

³ And when they shall blow with them, all the assembly shall assemble themselves to thee at the door of the tabernacle of the congregation.

⁴ And if they blow but with one trumpet, then the princes, which are heads of the thousands of Israel, shall gather themselves unto thee.