1 Samuel 17:33-35

And Saul said to David, “You are not able to go against this Philistine to fight with him, for you are but a youth, and he has been a man of war from his youth.” But David said to Saul, “Your servant used to keep sheep for his father. And when there came a lion, or a bear, and took a lamb from the flock, I went after him and struck him and delivered it out of his mouth. And if he arose against me, I caught him by his beard and struck him and killed him.