Numbers 10:3-8

³When they are sounded, all the people are to come together to you at the door of the Tent of meeting.

⁴If only one of them is sounded, then the chiefs, the heads of the thousands of Israel, are to come to you.

⁵When a loud note is sounded, the tents placed on the east side are to go forward.

⁶At the sound of a second loud note, the tents on the south side are to go forward: the loud note will be the sign to go forward.

⁷But when all the people are to come together, the horn is to be sounded but not loudly.

⁸The horns are to be sounded by the sons of Aaron, the priests; this is to be a law for you for ever, from generation to generation.