The Nature of the Nafs

Give in to the nafs, fail to purify it, fail to take care of it, and there is no possibility of victory over Shayṭān; one becomes his plaything instead, one of his party at all times. Allah (swt) addresses this directly in Sūrat al-Nāziʿāt:

Those who fear standing before their Lord and being called to account hold their nafs back from its appetite; they control it, out of fear of Allah, rather than being ruled by it. Anyone whose insight, whose baṣīrah, is truly open will find that most people today carry their nafs — a beast one is meant to ride — upon their own shoulders instead, walking about the streets beneath its weight. In outward form, ṣūratan, they appear as human beings; in inward reality, sīratan, they are, as Allah Himself says, worse than cattle. Those who instead fear Allah's station and hold their desire in check are promised Jannat al-Maʾwā, the greatest reward, on the Day of Judgement.

Left unchecked, the nafs will always incite toward evil; only through tazkiyah, purification, can its whisperings and those of Shayṭān be resisted. The nafs is essential to the Sharīʿah's understanding of the human being: it is the operating system within, an aspect of the rūḥ, the spirit. As the Messenger of Allah (peace be upon him) explains, at a certain stage within the womb an angel is sent to breathe the spirit into the forming child. From the moment the heartbeat begins, the rūḥ, entering this world, forgets entirely where it came from — the ʿālam al-arwāḥ — and, becoming enmeshed with the body, the jism, it grows confused and begins to develop tendencies and appetites. This appetite of the rūḥ is what is called the nafs. As a person's needs and wants grow, this place is loved more and more, its true origin in Allah forgotten, and the nafs begins to dominate the body and the intellect, demanding that everything be done to satisfy it — this is al-nafs al-ammārah.

Only through the discipline the Sharīʿah provides can this nafs be woken from its heedless sleep, its ghaflah, and returned by stages to its original, pure state, which is the rūḥ itself — moving, degree by degree, from al-nafs al-ammārah toward al-nafs al-muṭmaʾinnah, the soul at peace, of which Allah (swt) says:

It is not possible to kill oneself in pursuit of this: that would be suicide. What is meant when it is said that someone has "killed" the nafs is that its negative tendencies, its animal impulses, have been curbed and controlled — nothing more.