not for nothing do I, will they, etc....

not for nothing

For a specific or worthy reason. You see? Accidents can happen all too easily. It's not for nothing that we tell you to wear a seatbelt!
See also: not, nothing
Farlex Dictionary of Idioms.

not for ˈnothing do I, will they, etc. ...

used to emphasize that there is a good reason for something: Not for nothing did people call him the king of rock and roll.
See also: not, nothing, will
Farlex Partner Idioms Dictionary
See also:
  • by no means
  • not by any means
  • not for a second
  • not for a minute
  • not for a moment
  • aint
  • ain't
  • not for a instant
  • not for a/one minute/moment/second/instant
  • aren