1 Samuel 17:15

13The three oldest sons of Jesse had gone after Saul to the battle; and the names of his three sons who went to the battle were Eliab the firstborn, and next to him Abinadab, and the third Shammah.

14David was the youngest; and the three oldest followed Saul.

15Now David went back and forth from Saul to feed his father’s sheep at Bethlehem.

16The Philistine came near morning and evening, and presented himself forty days.

17Jesse said to David his son, “Now take for your brothers an ephah of this parched grain and these ten loaves, and carry them quickly to the camp to your brothers;