go back on word

go back on (one's) word

To not do something one said one would do; to renege on something. People are beginning to worry that the president is going to go back on his word and not lower taxes for lower-income families after all. You made a commitment to support our project, and now you've gone back on your word!
See also: back, go, on, word
Farlex Dictionary of Idioms.

go back on one's word

 and go back on one's promise; go back on one's pledge
to break a promise that one has made. I hate to go back on my word, but I won't pay you $100 afterall. Going back on your promise makes you a liar.
See also: back, go, on, word
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • (one) doesn't give a rip (about something)
  • (one) could use (something)
  • (one) doesn't give a hoot (about something)
  • (one) won't hear of (something)
  • (one) never would have guessed
  • (one's) heart is set on (something)
  • (one) could stand (something)
  • (I) wouldn't (do something) if I were you
  • all right
  • a fast talker