Tafsir of Al-Nas 114:4

الوسواس الخناس

The whisperer (Al-Waswas) who withdraws. "The devil who is squatting (perched) upon the heart of the Son of Adam. So when he becomes absentminded and heedless he whispers. Then, when he remembers Allah he withdraws.'' Mujahid and Qatadah also said this. Al-Mu`tamir bin Sulayman reported that his father said, "It has been mentioned to me that Shaytan is Al-Waswas. He blows into the heart of the Son of Adam when he is sad and when he is happy. But when he (man) remembers Allah, Shaytan withdraws.'' Al-`Awfi reported from Ibn Abbas;

الوسواس

The whisperer. "He is Shaytan. He whispers and then when he is obeyed, he withdraws.'' As for Allah's saying;

الذي يوسوس في صدور الناس