Numbers 10:9-10

When you go to war in your land against the adversary who attacks you, then you shall sound an alarm with the trumpets, that you may be remembered before the LORD your God, and be saved from your enemies. Also in the day of your gladness and in 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.”