Samuel and Empty things

Samuel was addressing the nation Israel when he was annointing Saul as king:

And Samuel said to the people, "Do not be afraid; you have done all this evil. Yet do not turn aside from following the Lord, but serve the Lord with all your heart. And do not turn aside after empty things that cannot profit or deliver, for they are empty."

I Samuel 12:20-21 (ESB).

Anything that is not done for the Lord is an empty thing.