1 Samuel 17:15-19

but David went back and forth from Saul to Bethlehem, where he took care of his father’s sheep. For forty days the Philistine came out every morning and evening and stood before the Israelite army. Jesse said to his son David, “Take this half bushel of cooked grain and ten loaves of bread to your brothers in the camp. Also take ten pieces of cheese to the commander and to your brothers. See how your brothers are and bring back some proof to show me that they are all right. Your brothers are with Saul and the army in the Valley of Elah, fighting against the Philistines.”