It's for a fact

It's for a fact.

Rur. It is true. Charlie: I can't believe that Bill's selling his house. Tom: It's for a fact! It's for a fact that chocolate is poison to cats.
See also: fact
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • known fact
  • fact of life
  • facts of life
  • a fact of life
  • as it so happens
  • there's no help for (something)
  • there's no help for it
  • fact
  • as it happens
  • know for a fact