Judges 7:16-19

16And he divided the three hundred men into three companies, and he put a trumpet in every man's hand, and empty pitchers, and torches within the pitchers.

17And he said to them, Look on me, and do likewise; behold, when I come to the extremity of the camp, it shall be that, as I do, so shall ye do.

18And when I blow with a trumpet, I and all that are with me, ye also shall blow the trumpets around the whole camp, and shall say, For Jehovah and for Gideon!

19And Gideon, and the hundred men that were with him, came to the outside of the camp in the beginning of the middle watch; and they had but newly set the watch; and they blew the trumpets, and broke the pitchers that were in their hands.