Joshua 6:3 (KJV)

Now Jericho was straitly shut up because of the children of Israel: none went out, and none came in.

And the LORD said unto Joshua, See, I have given into thine hand Jericho, and the king thereof, and the mighty men of valour.

And seven priests shall bear before the ark seven trumpets of rams' horns: and the seventh day ye shall compass the city seven times, and the priests shall blow with the trumpets.

And it shall come to pass, that when they make a long blast with the ram's horn, and when ye hear the sound of the trumpet, all the people shall shout with a great shout; and the wall of the city shall fall down flat, and the people shall ascend up every man straight before him.

And Joshua the son of Nun called the priests, and said unto them, Take up the ark of the covenant, and let seven priests bear seven trumpets of rams' horns before the ark of the LORD.

And he said unto the people, Pass on, and compass the city, and let him that is armed pass on before the ark of the LORD.

And it came to pass, when Joshua had spoken unto the people, that the seven priests bearing the seven trumpets of rams' horns passed on before the LORD, and blew with the trumpets: and the ark of the covenant of the LORD followed them.