1 Samuel 17:33-36

Then Saul said to David, “You are not able to go against this Philistine to fight him. For you are [only] a young man and he has been a warrior since his youth.” But David said to Saul, “Your servant was tending his father’s sheep. When a lion or a bear came and took a lamb out of the flock, I went out after it and attacked it and rescued the lamb from its mouth; and when it rose up against me, I seized it by its whiskers and struck and killed it. Your servant has killed both the lion and the bear; and this uncircumcised Philistine will be like one of them, since he has taunted and defied the armies of the living God.”