1 Samuel 17:38

And Saul armed David with his armour. — But the king was determined to omit no earthly means of securing victory to his young champion, and we read how he made him try on his own various pieces of fighting array, doubtless the best-tempered and costliest that the camp of Israel possessed. The word rendered “his armour” literally signifies his garments, that is, the dress worn beneath the mail. Upon this was buckled on the heavy metal armour suit, with the great fighting sword and the royal helm. It is not necessary to suppose David was at all of the same proportions as Saul, for much of the dress could have been speedily adjusted to the requirements of one slighter and shorter than the king; besides, the result shows they were, in spite of alteration, far too heavy and cumbersome. “I cannot go with these,” simply said the brave boy, his purpose, however, of meeting the Philistine giant quite unshaken, though he found his comparatively weak person unable to bear the weight of the king’s panoply or to wield his arms.