musalla vs sanctum sanctorum

musalla

noun
  • A place for praying (e.g. outside a mosque); a praying room. 

sanctum sanctorum

noun
  • A person's most private retreat or sanctuary. 

  • The Holy of Holies in the Jewish temple. 

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