Senses
一言既出，驷马难追/ 一言既出，駟馬難追 a promise must be kept
Literally "once a word is spoken, even a team of four horses cannot chase it back"; used to emphasize that a person must stand by their word and keep their promises.
一言既出，驷马难追/ 一言既出，駟馬難追 a word spoken cannot be withdrawn
once something is said, it cannot be taken back even by a team of four horses; a promise must be kept