Numbers 10:3-10

31When 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 2leaders, the heads of the 3divisions of Israel, shall assemble before you. 5But when you blow an alarm, the camps that are pitched 4on the east side shall set out. 6When you blow an alarm the second time, the camps that are pitched on 5the 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 6sounding an alarm. 87The priestly sons of Aaron, moreover, shall blow the trumpets; and 8this shall be for you a perpetual statute throughout your generations. 9When you go to war in your land against the adversary who 9attacks you, then you shall sound an alarm with the trumpets, that you may be 10remembered before the Lord your God, and be saved from your enemies. 10Also in the day of your gladness and in your appointed 11feasts, and on the first days of your months, 12you shall blow the trumpets over your burnt offerings, and over the sacrifices of your peace offerings; and they shall be as a reminder of you before your God. I am the Lord your God.”