suì​shì​bù​jiàn

let bygones be bygones

  1. bygones
    (literary) matters that have already taken place; things that have already run their course
  2. adverb
    not
    Negative adverb used before verbs, adjectives, and other adverbs to indicate negation; also used as a bound-form prefix to form terms with opposite meanings
  3. to admonish
    (bound form) to urge someone to correct their mistakes; to remonstrate, typically used for an inferior advising a superior