1 Chronicles 14:13-15
13-15And then the Philistines were back at it again, plundering in the valley. David again prayed to God. God answered, "This time don't attack head-on; circle around and come at them out of the balsam grove. When you hear a sound like shuffling feet in the tops of the balsams, attack; God will be two steps ahead of you, slaughtering the Philistines."
16David did exactly as God commanded, slaughtering Philistines all the way from Gibeon to Gezer.