Eliab his eldest brother heard when he spoke to the men; and Eliab's anger was kindled against David, and he said, Why are you come down? and 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.
"Eliab's anger was kindled"  (1 Samuel 17:28).  The reason for Eliab's anger is not readily discernible.  Some have ascribed it to "jealousy."[14] His mention of the sheep sounds unreasonable, because the bringing of supplies from their father made it clear that David had Jesse's permission to make the journey.  Perhaps Willis has the best explanation: "He was angry with David for associating with the soldiers, indirectly chastising them for not accepting Goliath's challenge, and implying that he (David) was able to defeat the giant."[15] That David had indeed indicated that he was able to fight the giant is clear from  1 Samuel 17:31.  "The very things with which Eliab charged his brother, presumption and wickedness of heart, were very apparent in Eliab's scornful reproof."[16]