Numbers 10:2-8

2“Make yourself two trumpets of silver, of hammered work you shall make them; and you shall use them for 1summoning the congregation and for having the camps set out.

32When both are blown, all the congregation shall gather themselves to you at the doorway of the tent of meeting.

4Yet if only one is blown, then the 3leaders, the heads of the 4divisions of Israel, shall assemble before you.

5But when you blow an alarm, the camps that are pitched 5on the east side shall set out.

6When you blow an alarm the second time, the camps that are pitched on 6the south side shall set out; an alarm is to be blown for them to set out.

7When convening the assembly, however, you shall blow without 7sounding an alarm.

88The priestly sons of Aaron, moreover, shall blow the trumpets; and 9this shall be for you a perpetual statute throughout your generations.