assure (EN)
verb

verb “assure”

assure; he assures; past assured, part. assured; ger. assuring
  1. to make someone feel confident that something is true or reliable
    The captain assured the passengers that the ship was unsinkable.
  2. to confirm or check that something is true or secure for oneself
    Before leaving on vacation, she assured herself that all the doors were locked.
  3. to guarantee that a particular outcome or event will occur
    Studying diligently for the entire semester will assure your success on the final exam.