Judges 7:16-18

And he divided the three hundred men into three companies, and he put a trumpet in every man's hand, with empty pitchers, and lamps within the pitchers. And he said unto them, Look on me, and do likewise: and, behold, when I come to the outside of the camp, it shall be that, as I do, so shall ye do. When I blow with a trumpet, I and all that are with me, then blow ye the trumpets also on every side of all the camp, and say, The sword of the LORD, and of Gideon.