They unite. This ḥāl (spiritual state) becomes manifest in the ʿārif's (gnostic's) nafs (the lower self). There is no word that can indicate it. However, along with his established knowledge of this state, the word closest to expressing it is prompted to him. Allah cannot unite with anything. Nothing can indwell in Him. (Ravza, 203)
Isār (altruistic preference): Isār is the act of considering the right of one's companion in companionship. It is to give up one's own share for the sake of one's companion's share, to bear hardship oneself so that one's companion may be at ease. For isār is to occupy oneself with helping others in accordance with the command of Allah, the Compeller, who commanded His chosen Messenger (peace be upon him). (Hujwīrī, 227)
Allah, Exalted is He, has said: "They give [others] preference over themselves, even though they are in privation." (al-Ḥashr 59:9) Isār is specification and choice (to make something exclusive and to prefer, to select). Preference, when done willingly, is beautiful, but it is also possible for it to be done without desire.
Isār has three degrees: The first degree is to prefer others over yourself in matters of the dunyā (this world) concerning things that are not forbidden to you, that you have no obstacle in attaining, and that will not waste your time. This can be realized through three things: honoring rights, abhorring miserliness, and inclining toward good akhlāq (character).
The second degree of isār is to prefer Allah's riḍā (contentment with God's decree) over the contentment of others, even if hardships are great, calamities are heavy, and even if endurance and the body are weakened because of it. This too can be achieved through three things: seeking severity (hardship), beautiful submission, and the strength of sabr (patient endurance). (Manāzil, 21)
The third degree of isār is to prefer Allah, Exalted is He. The summit of isār is to claim ownership in regard to property, then to abandon seeing your preference for Allah, and then to become absent even from this abandonment. (Manāzil, 22)
Abū Ḥafs said: Isār is to leave your own share and give precedence to your brothers' share, whether in matters of this world or the hereafter.
One of the Sufis said: Isār does not occur by choice. True isār is to see the right of others before your own right. In this, no distinction is made between brother, companion, or acquaintance.
One of the Sufis said: The ḥaqīqa (inner reality) of isār is to give your share of the hereafter to your brothers. In this way, the danger of the world, which is the place of preferring others over oneself, is minimized.
Isār is not an attribute belonging to the Real (God). It is only possible in a very remote sense, and to say so is improper. It has no real basis, and its abandonment is better. Such a thing only appears from those among the people of ecstatic utterance who lack knowledge and etiquette. In the ḥāl (spiritual state), we can say: Isār sometimes occurs as the kindness of one needy person to another needy person, and sometimes with need upon need.
Isbāt: Isār from the side of the Real is His bestowing wujūd (existence) upon an accident by means of a substance. Thus, His will pertains not to the locus of the substance, but to the creation of the substance itself. For the locus is necessarily subordinate to it. Indeed, the existence of the locus is a condition for the existence of the accident. The substance, however, is in need of the Real to create the accident in itself. For without the accident, there is no substance. The substance, whether spatially determined or not...