What is meant by “jinn and men” in Soorat al-Naas
Question

What is meant by “jinn and men” in Soorat al-Naas? Are they the devils among mankind and the jinn, or what?.
Praise be to Allah.Allaah says (interpretation of the meaning): 
Say: I seek refuge with (Allaah) the Lord of mankind,
2. The King of mankind —
3. The Ilaah (God) of mankind,
4. From the evil of the whisperer (devil who whispers evil in the hearts of men) who withdraws (from his whispering in one’s heart after one remembers Allaah).
5. Who whispers in the hearts of mankind.
6. Of jinn and men.”
[al-Naas 114:1-6]
In these verses is the command to seek refuge with Allaah from the whisperer who withdraws, who whispers into the hearts of mankind. 
It also tells us how that whisperer is, that he may be from among the jinn or he may be from among mankind. Al-Hasan said: both are devils; the devil from among the jinn whispers into people’s hearts, and the devil from among mankind comes openly. 
Qataadah said: among the jinn are devils and among mankind are devils, so seek refuge with Allaah from the devils of mankind and the jinn. 
This is the correct meaning of this verse. 
Ibn al-Qayyim (may Allaah have mercy on him) said:  
The correct view concerning the meaning of this verse is that the words “Of jinn and men” refer to the waswaas or whisper; there are two kinds of waswaas, one which comes from the jinn and one which comes from humans. The jinni whispers into the hearts of man and the human also whispers into the hearts of man… 
Similar to their having this whispering in common is the fact that they have devilish inspiration in common too. Allaah says (interpretation of the meaning): 
“And so We have appointed for every Prophet enemies — Shayaateen (devils) among mankind and jinn, inspiring one another with adorned speech as a delusion (or by way of deception)”
[al-An’aam 6:112]
The Shaytaan whispers his falsehood to a human being and the human being conveys it to other humans like him, so the devils of mankind and the jinn both share in the devilish inspiration and in the whispering… 
The verse indicates that we should seek refuge with Allaah from the evil of both types of devils – the devils among mankind and the devils among the jinn. End quote. 
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said in Tafseer Juz’ ‘Amma: 
The words “Of jinn and men” refer to the whispers that may come from the jinn or may come from the sons of Adam. 
The whispers of the jinn are clear, because they flow through the son of Adam like his blood.
 The whispers of the sons of Adam often come to a person and inspire him to do evil, making it appear attractive to him until these ideas gain control of him and he acts upon them. End quote. 
And Allaah knows best.