make no mistake about it

make no mistake about it

What I have said or am about to say is absolutely certain; do not think otherwise. I intend to take this all the way to the Supreme Court if I have to. Make no mistake about it. Make no mistake about it, this was a carefully orchestrated crime—not some amateur job.
See also: make, mistake, no
Farlex Dictionary of Idioms.

Make no mistake (about it)!

sent. an expression signifying the sincerity of the speaker’s previous statements. Make no mistake! This is the real thing.
See also: make, mistake, no
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • Make no mistake about it!
  • Make no mistake!
  • make no mistake
  • spit it out
  • Spit it out!
  • spit out
  • mean to say
  • you can bet the farm that (something will happen or is the case)
  • mean no offense
  • not mean any offense