Easton's Bible Dictionary
Jonah, Book of
Jonah and his story is referred to by our Lord (Matthew 12:39,40 ; Luke 11:29 ), a fact to which the greatest weight must be attached. It is impossible to interpret this reference on any other theory. This one argument is of sufficient importance to settle the whole question. No theories devised for the purpose of getting rid of difficulties can stand against such a proof that the book is a veritable history.
There is every reason to believe that this book was written by Jonah himself. It gives an account of (1) his divine commission to go to Nineveh, his disobedience, and the punishment following (1:1-17); (2) his prayer and miraculous deliverance ((1:17-2:10);); (3) the second commission given to him, and his prompt obedience in delivering the message from God, and its results in the repentance of the Ninevites, and God's long-sparing mercy toward them (ch. 3); (4) Jonah's displeasure at God's merciful decision, and the rebuke tendered to the impatient prophet (ch. 4). Nineveh was spared after Jonah's mission for more than a century. The history of Jonah may well be regarded "as a part of that great onward movement which was before the Law and under the Law; which gained strength and volume as the fulness of the times drew near.", Perowne's Jonah.
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain.
Easton, Matthew George. Entry for 'Jonah, Book of'. Easton's Bible Dictionary. http://www.studylight.org/dictionaries/ebd/j/jonah-book-of.html. 1897.