Numbers 10:5-9

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

Then when you sound an alarm the second time, the camps that are pitched on the south side shall set out; an alarm is to be sounded for them to break camp.

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

The sons of Aaron, moreover, the priests, shall blow the trumpets; and this shall be a permanent statute for you throughout your generations.

And when you go to war in your land against the enemy who attacks you, then you shall sound an alarm with the trumpets, so that you will be thought of by the Lord your God, and be saved from your enemies.