1 Samuel 17:32-36

And David said to Saul, “May no one’s heart fail on account of him; your servant will go and fight this Philistine!”

But Saul said to David, “You are not able to go against this Philistine to fight him; for you are only a youth, while 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 sheep from the flock,

I went out after it and attacked it, and rescued the sheep from its mouth; and when it rose up against me, I grabbed it by its mane and struck it 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 defied the armies of the living God.”