Question: What is the SHORTEST book of the Old Testament of the Bible?
Answer: Oops! The editor didn't read the question carefully and therefore published the WRONG answer! The Third Epistle of John is the shortest book when including BOTH Old and New Testaments, however, the question is asking ONLY for books of the Old Testament. The CORRECT answer for this question is Obadiah.
Read more:
http://overviewbible.com/the-5-shortest-books-of-the-bible-in-order/