2 Samuel 5:17-18
17-18When the Philistines got word that David had been made king over all Israel, they came on the hunt for him. David heard of it and went down to the stronghold. When the Philistines arrived, they deployed their forces in Raphaim Valley.
19Then David prayed to God: "Shall I go up and fight the Philistines? Will you help me beat them?"