In Islam, the Devil is known as Iblīs (Arabic: إبليس), Shayṭān, (Arabic: شيطان, plural: شياطين shayāṭīn) or Shaitan. His primary activity is to incite humans to commit evil and lead the wrong path through deception. which is referred to as "whispering into the hearts". The Quran mentions that there is not only one, but many satans. Satans are the assistants of those who disbelieve in God: "We have made the evil ones friends to those without faith."
Muhammad said that every man has his own satan. Some satans are attached to bad people and makes them evil. A satan runs in the blood of human beings. Another satan makes people forgetful or tries to interupt prayers to God.
Thes satans are actually human weakness. They call towards evil things, and influence human's mind. When a human dies, Iblis sometimes sends a satan as a last attempt to make him an unbeliever. This satan is sent to make the dying person disbelieving in God.