Sunan Abu-Dawud: Book 41, Number 4987: Bk 43.233
Narrated Abdullah ibn Amr ibn al−'As: The Apostle of Allah (peace_be_upon_him) said: Allah , the Exalted, hates the eloquent one among men who moves his tongue round (among his teeth), as cattle do.

Sunan Abu-Dawud: Book 41, Number 4988: Bk 43.234
Narrated AbuHurayrah: The Prophet (peace_be_upon_him) said: On the Day of resurrection Allah will not accept repentance or ransom from him who learns excellence of speech to captivate thereby the hearts of men, or of people.

Sunan Abu-Dawud: Book 41, Number 4989: Bk 43.235 (Android only)
Abd Allah b. Umar said : When two men who came from the east made a speech and the people were charmed with their eloquence, the Messenger of Allah (May peace be upon him) said: In some eloquent speech there is magic.

Sunan Abu-Dawud: Book 41, Number 4990: Bk 43.236
Narrated Amr ibn al−'As: One day when a man got up and spoke at length Amr ibn al−'As said If he had been moderate in what he said: It would have been better for him. I heard the Apostle of Allah (peace_be_upon_him) say: I think (or, I have been commanded) that I should be brief in what I say, for brevity is better.

Sunan Abu-Dawud: Book 41, Number 4993: Bk 43.239
Narrated Abdullah ibn Abbas: A desert Arab came to the Prophet (peace_be_upon_him) and began to speak. Thereupon the Apostle of Allah (peace_be_upon_him) said: In eloquence there is magic and in poetry there is wisdom.

Sunan Abu-Dawud: Book 41, Number 4994: Bk 43.240
Narrated Buraydah ibn al−Hasib: I heard the Apostle of Allah (peace_be_upon_him) say: In eloquence there is magic, in knowledge ignorance, in poetry wisdom, and in speech heaviness. Sa'sa'ah ibn Suhan said: The Prophet of Allah (peace_be_upon_him) spoke the truth. His statement "In eloquence there is magic" means: (For example), there is a right due from a man who is more eloquent in reasoning than the man who is demanding his right. He (the defendant) charms the people by his speech and takes away his right. His statement "In knowledge there is ignorance" means: A scholar brings to his knowledge what he does not know, and thus he becomes ignorant of that. His statement "In poetry there is wisdom" means: These are the sermons and examples by which people receive admonition. His statement "In speech there is heaviness" means: That you present your speech and your talk to a man who is not capable of understanding it, and who does not want it.