Numbers 10:6-8

New International Version

⁶ At the sounding of a second blast, the camps on the south are to set out.^(A) The blast will be the signal for setting out. ⁷ To gather the assembly, blow the trumpets,^(B) but not with the signal for setting out.^(C)

⁸ “The sons of Aaron, the priests, are to blow the trumpets. This is to be a lasting ordinance for you and the generations to come.^(D)