Numbers 10:7

5When you blow an alarm, the camps that lie on the east side shall go forward.

6When you blow an alarm the second time, the camps that lie on the south side shall go forward. They shall blow an alarm for their journeys.

7But 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. This shall be to you for a statute forever throughout your generations.

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