maintain vs unspeak

maintain

verb
  • To declare or affirm (a clause) to be true; to assert. 

  • To keep up; to preserve; to uphold (a state, condition etc.). 

unspeak

verb
  • To retract what one has spoken, to unsay. 

How often have the words maintain and unspeak occurred in a corpus of books? (source: Google Ngram Viewer )