Numbers 10:3-8

³And when thou shalt sound the trumpets, all the multitude shall gather unto thee to the door of the tabernacle of the covenant.

⁴If thou sound but once, the princes and the heads of the multitude of Israel shall come to thee.

⁵But if the sound of the trumpets be longer, and with interruptions, they that are on the east side, shall first go forward.

⁶And at the second sounding and like noise of the trumpet, they who lie on the south side shall take up their tents. And after this manner shall the rest do, when the trumpets shall sound for a march.

⁷But when the people is to be gathered together, the sound of the trumpets shall be plain, and they shall not make a broken sound.

⁸And the sons of Aaron the priest shall sound the trumpets: and this shall be an ordinance for ever in your generations.