Joshua 6:8-10

8And it was so. After Joshua had spoken to the people, seven kohanim carrying the seven shofarot of rams’ horns before Adonai went forward and blew the shofarot, and the ark of the covenant of Adonai followed them.

9Also the armed force went before the kohanim who blew the shofarot, and the rear guard came behind the ark, while the shofarot continued to blow.

10But Joshua ordered the people saying: “You must not shout nor let your voice be heard nor let a word proceed out of your mouth, until the day I tell you ‘shout!’ Then you will shout.”