Joshua 6:4-8

4Seven priests shall bear seven trumpets of rams' horns before the ark. On the seventh day you shall march around the city seven times, and the priests shall blow the trumpets.

5And when they make a long blast with the ram's horn, when you hear the sound of the trumpet, then all the people shall shout with a great shout, and the wall of the city will fall down flat, and the people shall go up, everyone straight before him."

6So Joshua the son of Nun called the priests and said to them, "Take up the ark of the covenant and let seven priests bear seven trumpets of rams' horns before the ark of the Lord."

7And he said to the people, "Go forward. March around the city and let the armed men pass on before the ark of the Lord."

8And just as Joshua had commanded the people, the seven priests bearing the seven trumpets of rams' horns before the Lord went forward, blowing the trumpets, with the ark of the covenant of the Lord following them.