Answer:

bible

Answer	Crossword Clue
BIBLE	Best-selling book of all time
BIBLE	Book that people take an oath on
BIBLE	Aid for administering an oath of office

BIBLE	See 33-Across
BIBLE	Swearing-in staple
BIBLE	Job holder?
BIBLE	... Belt
BIBLE	Daily reading for a pope
BIBLE	Book that might contain birth records
BIBLE	Oath taker's aid
BIBLE	Holy book

BIBLE	Job site?
BIBLE	Authoritative text
BIBLE	Kind of Belt