Charles Ellicott Commentary Numbers 10:7

"But when the assembly is to be gathered together, ye shall blow, but ye shall not sound an alarm." — Numbers 10:7 (ASV)

But you shall not sound an alarm. —A clear and intelligible distinction was to be made between the summons to the princes, or to the congregation, to assemble at the entrance of the Tent of Meeting and the signal for the moving of the camps. So the gospel trumpet must at no time give an uncertain sound (1 Corinthians 14:8), but must be used faithfully and diligently by the spiritual watchmen, whether it is to warn the ungodly, to arouse the careless, or to speak to the hearts of God’s people.