'Empty' in the Bible

Then he said, “Go, borrow containers from all your neighbors, empty containers—and not just a few.

They rejected His statutes and His covenant which He made with their fathers, as well as His warnings that he gave them. And they followed vanity [that is, false gods, idols] and became vain (empty-headed). They followed the [pagan practices of the] nations which surrounded them, although the Lord had commanded that they were not to do as they did.

You say (but they are only empty words) ‘I have counsel and strength for the war.’ Now on whom do you rely, that you have rebelled against me?