'Oldest' in the Bible

Jesse's three oldest sons had followed Saul to war. The names of the three sons who went to war were Eliab, his firstborn, Abinadab, the second oldest, and Shammah, the third oldest.

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

When David's oldest brother Eliab heard him speaking to the men, he became angry with David and said, "Why have you come down here? To whom did you entrust those few sheep in the desert? I am familiar with your pride and deceit! You have come down here to watch the battle!"

Then Saul said to David, "Here's my oldest daughter, Merab. I want to give her to you in marriage. Only be a brave warrior for me and fight the battles of the Lord." For Saul thought, "There's no need for me to raise my hand against him. Let it be the hand of the Philistines!"

They took captive the women who were in it, from the youngest to the oldest, but they did not kill anyone. They simply carried them off and went on their way.