Albert Barnes Commentary 1 Samuel 17:28

"And Eliab his eldest brother heard when he spake unto the men; and Eliab`s anger was kindled against David, and he said, Why art thou come down? and with whom hast thou left those few sheep in the wilderness? I know thy pride, and the naughtiness of thy heart; for thou art come down that thou mightest see the battle." — 1 Samuel 17:28 (ASV)

Why did you come down?—From the heights of Bethlehem to the valley of Elah.

Your pride and the wickedness of your heart—See the similar expression in Jeremiah 49:16. Compare the envy of Jacob’s sons toward Joseph and the slanders heaped upon the Son of David in the days of His flesh.