Sour Grapes means If you describe someone's behaviour or opinion as sour grapes, you mean that that person is angry because they have not got or achieved something that they wanted أن تُفرط فيما بين يديك/ ما يشتهيه المرء ولا يحصل عليه
https://dictionary.cambridge.org/dictionary/english/sour-gra...

bad behavior that happens because someone else is more successful:
So we can translate Sour Grapes also as الحقد

جدال حانق/حاقد/ساخط

التحجج هو الإستناد على حجج ليس لها أساس من الصحة أو أنها صحيحة ولكن استعملت في غيرمحلها

لقد تذوقوها بسبب صعوبة الوصول اليها

The expression "sour grapes argument" is an allusion to one of Aesop's famous fables, called "The Fox and the Grapes."

Aesop was a slave and storyteller who lived in Greece between 620 and 564 BC, and his fables have been popular since then. They have been translated to every known language, including Arabic, and are well-known all over the world. The great poet Ahmad Showqi even set many of these fables into verse, which I remember since elementary school. You can find an English-language version of the aforementioned fable here:

http://www.read.gov/aesop/005.html

"A Fox one day spied a beautiful bunch of ripe grapes hanging from a vine trained along the branches of a tree. The grapes seemed ready to burst with juice, and the Fox's mouth watered as he gazed longingly at them.

"The bunch hung from a high branch, and the Fox had to jump for it. The first time he jumped he missed it by a long way. So he walked off a short distance and took a running leap at it, only to fall short once more. Again and again he tried, but in vain.

"Now he sat down and looked at the grapes in disgust.

"What a fool I am," he said. "Here I am wearing myself out to get a bunch of sour grapes that are not worth gaping for."

"And off he walked very, very scornfully.

"There are many who pretend to despise and belittle that which is beyond their reach."

The last line above is the "wisdom of the fable." It is not known if these "wisdom lines" were original or added later by copyists and editors. Of course, like all fables, Aesop's can be interpreted in many different ways.

My main point is that the expression "sour grapes argument" is so well-known in the Arabic-speaking world that there is no need to try to explain the expression to the reader, unless you believe the addressed reader is ill-educated.

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Note added at 5 hrs (2020-03-31 20:32:26 GMT)
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One more point: The word argument in this sentence does not mean an argument between two parties. It means an argument presented by one person to another in support of his/her position. Therefore, it is not جدل or جدال, but rather حجة. For example, I am making an argument here, meaning I am making a presentation in support of my position.