Joshua 6:8-10

8And it was so, that, when Joshua had spoken unto the people, the seven priests bearing the seven trumpets of rams’ horns before Jehovah passed on, and blew the trumpets: and the ark of the covenant of Jehovah followed them. 9And the armed men went before the priests that blew the trumpets, and the rearward went after the ark, the priests blowing the trumpets as they went. 10And Joshua commanded the people, saying, Ye shall not shout, nor let your voice be heard, neither shall any word proceed out of your mouth, until the day I bid you shout; then shall ye shout.