'Labor In Vain' in the Bible

I have been condemned; why then should I labor in vain?

A Song of degrees for Solomon. Unless Jehovah builds the house, they labor in vain who build it; unless Jehovah keeps the city, the watchman stays awake in vain.

They will not labor in vain, nor bring forth for terror. For they are the seed of the beloved of Jehovah, and their offspring with them.

So says Jehovah of Hosts: The broad walls of Babylon shall be completely broken, and her high gates shall be burned with fire; and the people shall labor in vain, and the people shall be in the fire, and they shall be weary.