Numbers 10:8-10

Living Bible

⁸ Only the priests are permitted to blow the trumpets. This is a permanent instruction to be followed from generation to generation.

⁹ “When you arrive in the Promised Land and go to war against your enemies, God will hear you and save you from your enemies when you sound the alarm with these trumpets. ¹⁰ Use the trumpets in times of gladness, too, blowing them at your annual festivals and at the beginning of each month to rejoice over your burnt offerings and peace offerings. And God will be reminded of his covenant with you. For I am Jehovah, your God.”