Judges 7:16-18

16And he divided the 300 men into three companies and put trumpets into the hands of all of them and empty jars, with torches inside the jars.

17And he said to them, "Look at me, and do likewise. When I come to the outskirts of the camp, do as I do.

18When I blow the trumpet, I and all who are with me, then blow the trumpets also on every side of all the camp and shout, 'For the Lord and for Gideon.'"