'Oldest' in the Bible

David was the youngest. Now the three oldest followed Saul,

Now Eliab his oldest brother heard when he spoke to the men; and Eliab’s anger burned against David and he said, “Why have you come down? And with whom have you left those few sheep in the wilderness? I know your insolence and the wickedness of your heart; for you have come down in order to see the battle.”