rap over the knuckles vs reprove

rap over the knuckles

reprove

verb
  • to criticise, rebuke or reprimand (someone), usually in a gentle and kind tone. 

  • To prove again. 

  • to deny or reject (a feeling, behaviour, action etc.). 

  • to express disapproval. 

How often have the words rap over the knuckles and reprove occurred in a corpus of books? (source: Google Ngram Viewer )