And Saul said to David, thou art not able to go against
Philistine to fight with him
Had neither strength of body, nor skill in military affairs, to encounter with a man of his stature, and warlike genius and practice:
for thou [art but] a youth;
some say about fourteen or sixteen years of age, but very probably about twenty, and not more, and so not only weak, but inexpert in the art of fighting:
and he a man of war from his youth;
a gigantic man, trained up in, inured to, and expert in the affairs of war; so that David could not, on any account, be a competitor with him, and a match for him.