repudiate vs vouch for

repudiate

verb
  • To reject the truth or validity of; to deny. 

  • To be repudiated. 

  • To refuse to have anything to do with; to disown. 

  • To refuse to pay or honor (a debt). 

vouch for

verb
  • To affirm the truth or reliability of. 

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