Labor's Day- Fortune Cookie

Labor's Day fell on a Monday. Most people in America do not work on this day.
They stay home, have reunion, Bar-B-Que and Drink.
I did not go out too, stayed home, watch movie and Clean up the house.

Well, the Fortune cookie took a day off , too.

So what did the Labor's Day cookie said:

"Listen not to vain words of empty tongue"
What is an empty tongue? People who give empty promises? There are a lot of people
who can promise you everything, but no results.

Please give me your interpretation