Numbers 10:7

4 If they blow but one, then the princes, the heads of the thousands of Israel, shall gather themselves to you.

5 When you blow an alarm, the camps that lie on the east side shall take their journey.

6 When you blow an alarm the second time, the camps that lie on the south side shall take their journey: they shall blow an alarm for their journeys.

7 But when the assembly is to be gathered together, you shall blow, but you shall not sound an alarm.

8 The sons of Aaron, the priests, shall blow the trumpets; and they shall be to you for a statute forever throughout your generations.

9 When you go to war in your land against the adversary who oppresses you, then you shall sound an alarm with the trumpets; and you shall be remembered before Yahweh your God, and you shall be saved from your enemies.

10 Also in the day of your gladness, and in your set feasts, and in the beginnings of your months, you shall blow the trumpets over your burnt offerings, and over the sacrifices of your peace-offerings; and they shall be to you for a memorial before your God: I am Yahweh your God.