Numbers 10:6-8

New Revised Standard Version, Anglicised

⁶ when you blow a second alarm, the camps 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, you shall blow, but you shall not sound an alarm. ⁸ The sons of Aaron, the priests, shall blow the trumpets; this shall be a perpetual institution for you throughout your generations.