Sour grapes was originally thought to originate from the Aesop Fable The Fox and the Grapes. The Fox, upon not being able to reach the grapes, declares them sour so as to pretend to avoid his own disappointment. One of the translations goes like this:

A famished Fox saw some clusters of ripe black grapes hanging from a trellised vine. She resorted to all her tricks to get at them, but wearied herself in vain, for she could not reach them. At last she turned away, beguiling herself of her disappointment, and saying: “The Grapes are sour, and not ripe as I thought.

The phrase also appears in the Bible in Ezekiel. The question is, did the term enter the English language from the fable or the Bible?