cross one’s heart vs disclaim

cross one’s heart

disclaim

verb
  • To renounce all claim to; to deny ownership of or responsibility for; to disown; to disavow; to reject. 

  • To make an admission or warning. 

  • To deny, as a claim; to refuse. 

  • (law) To relinquish or deny having a claim; to disavow another's claim; to decline accepting, as an estate, interest, or office. 

How often have the words cross one’s heart and disclaim occurred in a corpus of books? (source: Google Ngram Viewer )