don't beat a dead horse

don't beat a dead horse

Don't continue to focus on some issue or topic that is no longer of any use or relevance. We've all moved on from that problem, so don't beat a dead horse.
See also: beat, dead, horse
Farlex Dictionary of Idioms.
See also:
  • don't go there
  • cart before the horse, don't put/set the
  • don't get me wrong
  • all in (one's) head
  • come it
  • come it (with one)
  • (I) won't tell a soul
  • cast (one's) lot in with (someone or something)
  • cast lot in