It is for this purpose. Meanwhile, what manifests are gluttony, the deceptions of the nafs (the lower self) and nature. (Hujwīrī, 390)
Hunger reduces the blood of the qalb (the heart) and whitens it. Its light is in its whiteness; this light melts the oil of the heart. In this melting lies the subtlety of the heart. Just as the hardness of the heart is the cause of veils, its subtlety is the key to unveiling (mukāshafa). (Iḥyāʾ, III, 94)
Hunger is the adornment of the awliyāʾ (friends of God). By this, I mean the habitualization of hunger. This is mawt-i abyāḍ (the white death).
The hunger deemed appropriate for the righteous (ṣāliḥūn) on the Sufi path is to reduce the excesses of (personal) nature and to choose to desire the world without needing to act for it. If the aspiration rises, it seeks the attribute of Ṣamadiyya (Divine Self-Sufficiency). Its limit, according to us, is a single day of fasting. If sleeplessness is added to this, it becomes a legitimate and voluntary hunger. This is, for us, a path that can only be considered legitimate. If Allah had not limited this necessity for the common people (ḥalq), their state could not approach this degree.
A human cannot know the benefits that come to the servant from increased hunger better than his Lord. To think otherwise is the utmost degree of bad etiquette. If, during the night (in worship) and in his fanāʾ (annihilation in God), he finds himself fed and given drink by another state, and finds its effect in his strength, the soundness of his intellect, and the preservation of his temperament, he attains what he desires. He is not fit for hunger.
Our discourse on hunger, even if it concerns the One who leads him to the state of absorption (istighrāq), sometimes, as with Abū Uqqāl, a powerful influx (wārid) intervenes between him and hunger. If he derives benefit from this, this is what is intended and sought by the Sufis. If no benefit is obtained, it is an illness and this state should be referred to a physician (to be treated). This is not a state aimed at by the Sufis. The hunger of the great ones is a forced (iḍṭirārī, involuntary) hunger. That which leads to hunger in them becomes a malaka (a firmly rooted disposition) that does not disappear with either hunger or satiety. They suffice with little. However, they abstain from the lawful either for vigor in acts of obedience or to lighten the reckoning. (Futūḥāt, II, 184)
Mawt-i abyāḍ is hunger. For hunger illuminates the inside of a person and brightens the face of the heart. If the sālik (traveler) does not fill his stomach and continues to remain hungry, he dies the white death. Then, he gives life to his intelligence, for gluttony kills intelligence. Whoever kills his gluttony revives his intelligence. (Kāshānī, 92; Jāmiʿ, 100)
Hunger thins black blood and dries up arrogance in the heart. With it, the emptiness in the spirit (rūḥ) disappears. In the passages of hunger, the flashes of unveiling (mukāshafa) shine. (Rawḍa, 470)
There are four conditions for entering the Sufi path: hunger (eating little), seclusion, sleeping little, and speaking little. If the murīd (aspirant, disciple) can manage to remain hungry (eat little), the other three conditions follow. For hunger (eating little) leads to speaking little, increases wakefulness (thus enables sleeping little), and (thus the murīd) comes to enjoy being apart from people. (Anwār, 56)