tell tales out of school vs vouchsafe

tell tales out of school

verb
  • To reveal confidential or sensitive information; to gossip. 

vouchsafe

verb
  • To disclose or divulge. 

  • To graciously give, to condescendingly grant a right, benefit, outcome, etc.; to deign to acknowledge. 

  • To receive or accept in condescension. 

How often have the words tell tales out of school and vouchsafe occurred in a corpus of books? (source: Google Ngram Viewer )