誓不反悔

shìbùfǎnhuǐ
to vow not to break one's promise

CEDICT

Entry Composition

1 誓 shì
  1. oath
  2. vow
  3. to swear
  4. to pledge
2 不 bù
  1. no; not so
  2. (bound form) not; un-
3 反悔 fǎnhuǐ
  1. to renege
  2. to go back (on a deal)
  3. to back out (of a promise)