Numbers 10:6-8

Revised Standard Version

⁶ And when you blow an alarm the second time, the camps that are on the south side shall set out. An alarm is to be blown whenever they are to set out. ⁷ But when the assembly is to be gathered together, you shall blow, but you shall not sound an alarm. ⁸ And the sons of Aaron, the priests, shall blow the trumpets. The trumpets shall be to you for a perpetual statute throughout your generations.