一言既出，驷马难追 (一言既出，駟馬難追) yīyán jì chū, sì mǎ nán zhuī

yīyán jì chū, sì mǎ nán zhuī phrase once said, a team of horses cannot unsay it; a promise must be kept
Domain: Proverb 谚语
Notes: (CC-CEDICT '一言既出，駟馬難追')