Non-Master of Divinity Bible students love to point out that it was a fish, not a whale, that swallowed Jonah, according to the scriptures.

Jesus, however, used a word that everybody understood as meaning "whale" when He mentioned the Jonah incident in Matthew 12:40.

Here's more about whales in the Bible from the book "1001 More Things You Wanted to Know About the Bible:"

We learn very early in the Bible that "God created great whales" (Gen. 1:21). They are mentioned only a few times in the Bible, though we can assume that when the book of Jonah says that the prophet was swallowed by a "great fish," what actually swallowed Jonah was a whale (which is, technically, a mammal). In fact, though a "great fish" swallowed Johah, when Jesus spoke of the incident He referred to the "whale" that swallowed him (Matt. 12:40). (For the record: yes, largew whales like the sperm whale can swallow a man, and, yes, men have been swallowed and lived to tell it.)

There is a possibility that the water monster Leviathan may have been a whale instead of a mythical monster.

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You have done many good things for me, Lord, just as you promised. I believe in your commands; now teach me good judgment and knowledge. Psalm 119:65-66 NLT