Their trumpets That is, the trumpets belonging to the whole army, which he retained for the use following. Gideon seems to have been now inspired with the thought of the stratagem which he put in execution afterward, otherwise he would not have ordered every one of the three hundred to take a trumpet in his hand.
Related Commentaries of Judges 7:8
Judges 7:8
8 So the people took victuals in their hand, and their trumpets: and he sent all the rest of Israel every man unto his tent, and retained those three hundred men: and the host of Midian was beneath him in the valley.