1 Samuel 17:32

28 Now when David’s oldest brother Eliab heard him speaking to the men, his anger burned against David. “Why have you come down here?” he asked. “And with whom did you leave those few sheep in the wilderness? I know your pride and wickedness of heart—you have come down to see the battle!”

29 “What have I done now?” said David. “Was it not just a question?”

30 Then he turned from him toward another and asked about the offer, and those people answered him just as the first ones had answered.

31 Now David’s words were overheard and reported to Saul, who called for him.

32 And David said to Saul, “Let no man’s heart fail on account of this Philistine. Your servant will go and fight him!”

33 But Saul replied, “You cannot go out against this Philistine to fight him. You are just a boy, and he has been a warrior from his youth.”

34 David replied, “Your servant has been tending his father’s sheep, and whenever a lion or a bear came and carried off a lamb from the flock,

35 I went after it, struck it down, and delivered the lamb from its mouth. If it reared up against me, I would grab it by its fur, strike it down, and kill it.

36 Your servant has killed lions and bears; this uncircumcised Philistine will be like one of them, for he has defied the armies of the living God.”

Read all of 1 Samuel 17