Numbers 10:8-10

New Revised Standard Version, Anglicised Catholic Edition

⁸ The sons of Aaron, the priests, shall blow the trumpets; this shall be a perpetual institution for you throughout your generations. ⁹ When you go to war in your land against the adversary who oppresses you, you shall sound an alarm with the trumpets, so that you may be remembered before the Lord your God and be saved from your enemies. ¹⁰ Also on your days of rejoicing, at your appointed festivals, and at the beginnings of your months, you shall blow the trumpets over your burnt-offerings and over your sacrifices of well-being; they shall serve as a reminder on your behalf before the Lord your God: I am the Lord your God.