1 Samuel 17:15-19

but David went back and forth from Saul to tend his father’s flock at Bethlehem. The Philistine [Goliath] came out morning and evening, and took his stand for forty days. Then Jesse said to David his son, “Take for your brothers an ephah of this roasted grain and these ten loaves of bread and run quickly to the camp to your brothers. Also take these ten cuts of cheese to the commander of the unit. See how your brothers are doing and bring back news of them. Now they are with Saul and all the men of Israel in the Valley of Elah, fighting with the Philistines.”