And David girded his sword upon his armour, and he assayed to go; for he had not proved it. And David said unto Saul, I cannot go with these; for I have not proved them. And David put them off him.
David is at length presented to Saul for his champion (Sa1 17:31) and he bravely undertakes to fight the Philistine (Sa1 17:32): Let no man's heart fail because of him. It would have reflected too much upon the valour of his prince if he had said, Let not thy heart fail; therefore he speaks generally: Let no man's heart fail.
Commenting on 1 Samuel 17:31-39
And David girded his, sword upon his armour,.... Which Saul also perhaps furnished him with: and he assayed to go; made an attempt, and had a mind to go thus accoutred; he at first showed an inclination to go in such an habit, but afterwards would not: for he had not proved it; as warriors were wont to do; so Achilles did (i); he never...
I cannot go with these - In ancient times it required considerable exercise and training to make a man expert in the use of such heavy armor; armor which in the present day scarcely a man is to be found who is able to carry; and so it must have been then, until that practice which arises from frequent use had made the proprietor perfect.