Shaykh Ibrāhīm al-Khawwāṣ (may Allah grant him His mercy) said,

The beginning of sin is the (random) evil notion (خاطر).

If its owner does not obviate it by disliking it, it will become (a persistent) resistance.

If its owner does not obviate it by resisting it, it becomes whispering.

If its owner does not correct it through discipline, from it will awaken lusts with [his] capriciousness, and it will obstruct one’s mind, knowledge, and clear distinction. (Leading to sinful involvement.)

The infamies of the soul and their treatment (edit)