Numbers 10:4

But if they blow only one, then the leaders, the heads of the divisions of Israel, shall gather to you.

Surrounding context

10:3 When they blow both of them, all the congregation shall gather before you at the door of the tabernacle of meeting.

10:4 But if they blow only one, then the leaders, the heads of the divisions of Israel, shall gather to you.

10:5 When you sound the advance, the camps that lie on the east side shall then begin their journey.

Translation and sources