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 camest thou down hither? and with whom hast thou left those few sheep in the wilderness? I know thy pride, and the naughtiness of thine heart; for thou art come down that thou mightest see the battle.
David, the young shepherd, came down to Israel's camp on his father's errand to bring a message and a gift of provisions to his brothers and to learn what was happening there. It was on that errand that he heard Goliath defy Israel. His eldest brother Eliab heard him speaking to the men, and his anger was kindled against him. Eliab belittled his work of tending those few sheep in the wilderness as abandoned and left unattended, and charged him with pride and naughtiness of heart, saying he had come down only to see the battle.
That accusation was false and unjust, a mistaken judgment of David's motives. It arose from jealousy of the honor shown to David and from contempt for him as inferior. David rejected the unjust charge, answering respectfully but firmly that there was a cause for his concern about Israel. In truth he was moved by zeal to defend God's honor and His people. His courage in facing Goliath came from humility and trust in God.
He thus stands as an example of relying on God rather than boastful confidence in human strength and self-confidence or in prepared arguments.