(Sermon starts at 27:45 in the recording).
3 You shall march around the city, all you men of war; you shall go all around the city once. This you shall do six days. 4 And seven priests shall bear seven trumpets of rams’ horns before the ark. But the seventh day you shall march around the city seven times, and the priests shall blow the trumpets. 5 It shall come to pass, when they make a long blast with the ram’s horn, and when you hear the sound of the trumpet, that all the people shall shout with a great shout; then the wall of the city will fall down flat. And the people shall go up every man straight before him.”
6 Then 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.” 7 And he said to the people, “Proceed, and march around the city, and let him who is armed advance before the ark of the Lord.”
8 So it was, when Joshua had spoken to the people, that the seven priests bearing the seven trumpets of rams’ horns before the Lord advanced and blew the trumpets, and the ark of the covenant of the Lord followed them. 9 The armed men went before the priests who blew the trumpets, and the rear guard came after the ark, while the priests continued blowing the trumpets.
Joshua 6:3-9 (NKJV)