Numbers 10:3-5

Amplified Bible

³ When both are blown, all the congregation [that is, all adult males] shall gather before you at the doorway of the Tent of Meeting (tabernacle). ⁴ However, if a single trumpet is blown, then the leaders, heads of the tribes of Israel, shall gather themselves to you. ⁵ When you blow an alarm, the camps on the east side [of the tabernacle] shall set out.