Numbers 10:6-10

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.

Also on the day of your joy and at your appointed feasts, and on the first days of your months, you 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.” The Tribes Leave Sinai