1 Samuel 17:39

David strapped his sword on his clothing and he tried to move, for he had not tested it. David said to Saul, “I can’t go with these, for I have not tested them.” Then David took them off.

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.