The three older sons of Jesse had followed Saul into battle: The firstborn was Eliab, the second was Abinadab, and the third was Shammah.
KJV
And the three eldest sons of Jesse went [and] followed Saul to the battle: and the names of his three sons that went to the battle [were] Eliab the firstborn, and next unto him Abinadab, and the third Shammah.
ASV
And the three eldest sons of Jesse had gone after Saul to the battle: and the names of his three sons that went to the battle were Eliab the first-born, and next unto him Abinadab, and the third Shammah.