I Samuel 17:33

33 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."

33 And Saul said to David, You are not able to go out against this Philistine and have a fight with him: for you are only a boy, and he has been a man of war from his earliest days.