Correct
一言既出，驷马难追
/ yī yán jì chū, sì mǎ nán duī /
Strokes
Definition
lit. once said, a team of horses cannot unsay it (idiom); a promise must be kept
Example
Definition
words once uttered cannot be taken back even by a team of four horses—what is said cannot be unsaid; a word spoken can never be taken back