'Vain' in the Bible

Thou shalt not take the name of the LORD thy God in vain: for the LORD will not hold him guiltless that taketh his name in vain.

Your sons and daughters will be given to another people while you look on in vain all day, and you will be powerless to do anything about it.

For it is not a vain thing for you; because it is your life: and through this thing ye shall prolong your days in the land, whither ye go over Jordan to possess it.