yì​zhī​suǒ​zài

where duty lies

  1. justice
    (bound form) justice; righteousness; upright behavior
  2. 之 zhī particle
    [possessive]
    Connects a describing word or phrase to the noun it describes, similar to 的 de but used in formal or literary writing.
  3. where something lies
    the place where something exists or resides, often used after a noun to indicate the heart or essence of a matter