1 Samuel 17:32-36

David said to Saul, “Let no one lose heart on account of this Philistine; your servant will go and fight him.” Saul replied, “You are not able to go out against this Philistine and fight him; you are only a young man, and he has been a warrior from his youth.” But David said to Saul, “Your servant has been keeping his father’s sheep. When a lion or a bear came and carried off a sheep from the flock, I went after it, struck it and rescued the sheep from its mouth. When it turned on me, I seized it by its hair, struck it and killed it. Your servant has killed both the lion and the bear; this uncircumcised Philistine will be like one of them, because he has defied the armies of the living God.