And the Philistines came up yet again, and spread out in the valley of Reph′aim. And when David inquired of the Lord, he said, “You shall not go up; go around to their rear, and come upon them opposite the balsam trees. And when you hear the sound of marching in the tops of the balsam trees, then bestir yourself; for then the Lord has gone out before you to smite the army of the Philistines.” And David did as the Lord commanded him, and smote the Philistines from Geba to Gezer.
–2 Samuel 5:22-25