The words and ideas that the Shaitans whisper into a person's heart to tempt them to do sinful things.

The word wiswas is found in the Quran in Surat Al Naas (The People).
-In the name of Allah, Most Gracious, Most Merciful-
[114.1] Say: I seek refuge in the Lord of men,
[114.2] The King of men,
[114.3] The God of men,
[114.4] From the evil of the whisperings of the slinking (Shaitan),
[114.5] Who whispers into the hearts of men,
[114.6] From among the jinn and the men.