1 Samuel 17:33-35

Then Saul said to David, “You are not able to go against this Philistine to fight with him; for you are but a youth while he has been a warrior from 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 from the flock, I went out after him and attacked him, and rescued it from his mouth; and when he rose up against me, I seized him by his beard and struck him and killed him.