commendation vs rap over the knuckles

commendation

noun
  • The act of commending; praise; favorable representation in words; recommendation. 

  • That which is the ground of approbation or praise. 

  • A message of affection or respect; compliments; greeting. 

  • An award or recognition for performance; a medal. 

rap over the knuckles

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