I must confess, I've never had to use this one, but someone out there might find it helpful.
To abjure is to deny or renounce under oath, e.g. "The defendant abjured the charge of murder," or to declare one’s permanent abandonment of a place, eg. abjure the realm.
To adjure is to require someone to do something as if under oath, e.g. "I adjure you to keep this secret," or to urge earnestly, e.g. "The executive committee adjured all the members to approve the plan."