The Eloquent Speech Of The Prophet (saw) Are Known To The Scholars
From the signs in the text of a narration that point to its fabrication is when the matn (text) is of a stilted or awkward speech, lacking the Arabic eloquence.
The scholar who is familiar with the intricate details of the Arabic language knows when a given word or phrase is stiff or stilted (artificial, unnatural) and concludes that it is impossible to have emanated from one who is eloquent and well spoken – how then could such words have emanated from the most eloquent person to have ever spoken Arabic, Muhammad (saw)?
Al-Haafidh Ibn Hajr pointed out that this is sign is valid when exact words of the Prophet (saw) are being quoted.
Ibn Daqeed Al-‘Eed said:
“Scholars often rule a narration to be fabricated based on this principle – based on the wording of the narration. Because of their extensive research in hadeeth literature, they have developed string mental and spiritual faculties, through which they are able to differentiate between what the prophet (saw) might have uttered and what the Prophet (saw) could not have uttered.”
“If one serves under a master for a number of years, he knows what he loves and what he hates, so if a third party were to claim that the master hated something, while the servant knew for a fact that he loved that things, he would, immediately upon hearing the claim, reject it as a lie.”
For example scholars of this field are known to have statements like “There is darkness upon this hadeeth,” or “Its text is dark,” or “The heart denies it,” or “The soul does not find peace in it.”
Ar-Rabee’ Ibn Khuthaym said:
“Among hadeeths, there is the hadeeth that has the illumination of the day, by which you know it (to be true). And among hadeeths there is the hadeeth that has the darkness of the night, by which you know it (to be false).”
Ibn Al-Jawzee said:
“The skin of the student of knowledge quivers upon hearing the munkar hadeeth (that which is unauthentic as well as contradicting the authentic). And most of the time his heart has an aversion to it.”
[The Sunnah And Its Role In Islamic Legislation” p. 139]