Xenophon, Cyropaedia
Walter Miller, Ed.

And first of all he received quartermasters from Cyaxares and commanded them to furnish ready made for each of the soldiers a liberal supply of everything that he needed. And when he had provided for this, he had left them nothing to do but to practise the arts of war, for he thought he had observed that those became best in any given thing who gave up paying attention to many things and devoted themselves to that alone. So, in the drill itself he relieved them of even the practice with bow and spear and left them only the drill with sword and shield and breastplate. And so he at once brought home to them the conviction that they must go into a hand-to-hand encounter with the enemy or else admit that as allies they were good for nothing. But such an admission is hard for those who know that they are being maintained for no other purpose than to fight for those who maintain them.