1 Samuel 17:14 in the King James Version
And David was the youngest: and the three eldest followed Saul.
Context
13 The 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.
14 David was the youngest; and the three oldest followed Saul.
15 Now David went back and forth from Saul to feed his father’s sheep at Bethlehem.