Najmuddin Kubra has given a short summary of the subject of discerning one’s thoughts:
The first is the thought that is from God, and the sign of that thought is that it enters the heart spontaneously, and one should not deny that thought. In reality one cannot do so, but that is the practice of beginners, that they do deny it, because the beginner has not yet distinguished it from the thoughts that come from the master.
The second is the thought from the heart, and the third is the thought from the angel. These two are close to each other, yet between the thought from the heart and the thought from the angel there is a subtle difference. You will know this difference from the situation of the messenger (). He was chivalrous, in the month of Ramadan he was more chivalrous, and when Gabriel was near, he was still more chivalrous. So you realise that, from the presence of the angel and his thoughts, chivalry is increased.
Fourth is the thought from the carnal soul. Fifth is the thought from Satan. These two thoughts are close to one another, but between the two thoughts there is a difference. That is, when the carnal soul desires something and does not get it, it continues to desire it. In the desire for that thing, conflicts appear. But when Satan commands something that is a sin, if man does not do sit, Satan wants him to do something else, for his goal is to mislead.
Another difference between the thought from the heart and the angel on the one hand, and the thought from the carnal soul and Satan on the other, is that the thoughts from the heart and the angel seek nearness to God Most High, and they incline toward the satisfaction of God Most High and the attainment of the reward of the next world. The carnal soul and Satan avoid nearness to God Most High, and they incline toward worldly vanities and passionate desires. Another difference is that the thoughts from the angel and the heart produce peace and quietude of the heart without internal objection. But in the thoughts of the carnal soul and Satan an internal heaviness appears, and from every corner objections appear.
Another difference is that the heart and the angel desire all that is praiseworthy in all circumstances, while the carnal soul and Satan desire all that is blameworthy in all circumstances. Another difference is that the thought of the heart and the angel are in agreement with the Book of God and the example of the Messenger, while the thought of the carnal soul and Satan are in conflict with the Book of God, with the heart, with the angel, and with the example of the Messenger. Another difference is that the thought of the angel and the heart increases certainty, but from the thought of the carnal soul and Satan, doubt and deception enter. Another difference is that the thought of the angel and the heart are of the type of thought that is near the moment of death, and the thought of the carnal soul and Satan is of the kind of thought that appears at the time of bodily health and happiness. Another difference is that at the time of the thought of the angel and the heart, witnessing becomes more pure and obscurity departs, while the thought of the carnal soul and Satan has no other character than obscurity and heaviness of heart.