yǐ​zhí​bào​yuàn​yǐ​dé​bào​dé

to repay kindness with kindness and enmity with justice

  1. to meet resentment with fairness
    To handle a grudge or treat those who have wronged you with impartiality and justice; a concept from the 论语 lún​yǔ, contrasted with responding with kindness or further hatred.
  2. non-Chinese
  3. one good turn deserves another
    to return kindness for kindness; to repay a favor with a favor