jūn​zǐ​yī​yán​sì​mǎ​nán​zhuī

a nobleman's word is his bond

  1. gentleman
    A man of noble character, integrity, and virtue; often contrasted with 小人 xiǎo​rén.
  2. one word
    a single word, a brief remark, or one sentence
  3. non-Chinese
  4. what is said cannot be unsaid
    A team of four horses cannot catch up with a spoken word; used to mean that once something is said, it cannot be taken back