Numbers 10:7-9

New Century Version

⁷ When you want to gather the people, blow the trumpets, but don’t blow them as loudly.

⁸ “Aaron’s sons, the priests, should blow the trumpets. This is a law for you and your descendants from now on. ⁹ When you are fighting an enemy who attacks you in your own land, blow the trumpets loudly. The Lord your God will take notice of you and will save you from your enemies.