'Eldest' in the Bible

The three eldest 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.

David was the youngest; and the three eldest followed Saul.

Eliab his eldest brother heard when he spoke to the men; and Eliab's anger was kindled against David, and he said, "Why have you come down? With whom have you left those few sheep in the wilderness? I know your pride, and the naughtiness of your heart; for you have come down that you might see the battle."