Numbers 10:7-9 Common English Bible (CEB)
7 To gather the assembly, blow a long blast, not a series of short blasts. 8 Aaron’s sons the priests will blow the trumpets. This will be a permanent regulation for you throughout time.
9 When you go to war in your land against an enemy who is attacking you, you will blow short blasts with the trumpets so that you may be remembered by the Lord your God and be saved from your enemies.