I Samuel 17:13-15

The three oldest sons of Jesse had gone to follow Saul to the battle. The names of his three sons who went to the battle were Eliab the firstborn, next to him Abinadab, and the third Shammah. David was the youngest. And the three oldest followed Saul. But David occasionally went and returned from Saul to feed his father’s sheep at Bethlehem.