Numbers 10:6-8

Lexham English Bible

⁶ when you blow a second blast, the camps that are camping on the south will set out; they will blow a blast for their journeys. ⁷ But when summoning the assembly, you will blow, but you will not signal with a loud noise. ⁸ The sons of Aaron, the priests, will blow on the trumpets; this will be an eternal decree for your generations.