preaching to the choir

predicar a los conversos

• You're preaching to the choir — I've been making that case for months.
• Telling environmentalists to recycle more is preaching to the choir.
• Explaining the benefits of exercise to a fitness trainer is preaching to the choir.

This idiom is mostly used in informal contexts, both spoken and written, when someone is emphasizing something that is already obvious to their audience. It's often heard in debates or discussions where the listeners do not need convincing because they already agree.

Spanish speakers sometimes say 'preaching to the chorus' instead of 'choir'. This is incorrect because in English it's 'choir', not 'chorus'.

• the best-laid plans of mice and men
  el hombre propone y Dios dispone
• in the thick of it
  en plena vorágine, en lo más intenso
• have a finger in every pie
  tener un dedo en cada pastel, estar metido en todo
• above board
  transparente, legítimo, sin trampas