Jūnzǐ yī yán, sìmǎ-nánzhuī.

君子一言, 駟馬難追。

Lit Once a gentleman [has given his] word, a team of four horses cannot overtake it.

Fig A gentleman never goes back on his word.

Note [Note: sìmǎ-nánzhuī is used as a chengyu meaning “What has been said cannot be unsaid”; see also yī yán jì chū below.]

Topics chengyu COMMITMENT GENTLEMEN HONOR PROMISES sìmǎ-nánzhuī TRUST