Numbers 10:3-8

³The priests must blow the trumpets to call all the community together in front of you at the entrance to the tent of meeting.

⁴If the priests blow only one trumpet, then the leaders, the heads of the clans of Israel, must gather to you.

⁵When you blow a loud signal, the camps on the east side must begin their journey.

⁶When you blow a loud signal the second time, the camps on the south side must begin their journey. They must blow a loud signal for their journeys.

⁷When the community gathers together, blow the trumpets, but not loudly.

⁸The sons of Aaron, the priests, must blow the trumpets. This will always be a regulation for you throughout your people's generations.