imprecation vs precation

imprecation

noun
  • The act of imprecating, or invoking evil upon someone; a prayer that a curse or calamity may befall someone. 

  • A curse. 

precation

noun
  • A prayer or act of praying; an earnest request. 

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