Al-Shaykh al-Akbar Ibn Arabi:
Know - may Allah aid you - that fasting (sawm) means both 'abstention' and 'elevation': sam al-nahar means 'the day rose'; Imru' al-Qays used the verb in this way. Because fasting is elevated in rank above all other acts of worship, it is called sawm. God raised it by making it incomparable, out of all the acts of worship, as we shall see; and He took it from His servants even as they worshipped Him by it, and ascribed it to His own Self; and He rewards those who do it by His own hand from His own vessel; and He connected it to Himself by calling it incomparable.
Now fasting is not really an abstention, not an action; and the fact that it is called incomparable makes it all the more apt to be connected with Him; for He says about Himself: "There is nothing like unto Him" (42:11). With this He negates that anything could be comparable to Him; and thus He is incomparable according to both reason and revelation. Nisa'i relates that Abu Umama said: 'I went to the Messenger of God (God bless him and give him peace) and said, "Command me with something that I can take from you." He said: "You must fast, for there is nothing like it."' With this, he negated that any other act of worship God established for His servants is like it. Anyone who understands that fasting is a negative attribute - since it means to abstain from all that vitiates it - will understand for certain that there is nothing like it, for it does not have any essence that could be rationally said to exist. This is why God says 'the fast is Mine', since in reality it is neither worship nor act. To call it an action is barely tolerable, just as to say that the Real (as we understand it) 'exists' is barely tolerable - for the existence ascribed to Him whose Existence is identical with His Essence in no way resembles the existence ascribed to us, for "there is nothing like unto Him."
Consider this Divine Hadith, narrated by Muslim on the authority of Abu Hurayra: The Messenger of Allah (upon whom be blessings and peace) said: 'Allah, Almighty and Glorious, says: "Every act of the Son of Adam is his, save for fasting, which is Mine, and I reward it." Fasting is a shield; and on the day when one of you fasts, let him speak neither obscenely nor loudly; and if anyone curses him or fights him, let him say: "I am fasting." By Him in whose hand is the soul of Muhammad, the changed smell of the mouth of the one who fasts is more fragrant to God, on the Day of Resurrection, than the scent of musk. The one who fasts rejoices in two joys: when he opens his fast, he rejoices in it; and when he meets his Lord, he rejoices in his fast.'
Know that since, as the hadith of Nisa'i has established, God declared fasting to be incomparable, and the Real is incomparable, the one who fasts meets his Lord in the attribute of "there is nothing like unto Him"; thus he sees Him by it, and He is both the Seer and the Seen. This is why the Prophet said 'he rejoices in his fast', not 'he rejoices in the meeting with his Lord'; for joy does not cause joy in and of itself, but rather is the conduit of joy felt in something else. If the Real is one's sight when he sees and witnesses, then he sees himself only through His sight. The one who fasts rejoices in attaining unto the rank of incomparability. He rejoices in breaking the fast in this world because of the satiation of the animal self which innately desires nourishment for itself; and when the gnostic sees the need that his animal and vegetative self has for nourishment, and sees His largess in providing the nourishment he gives it, thereby fulfilling its right (haqq), as God obliged him to, he thereby acts with the attribute of truth (haqq). Thus he gives with the hand of God, just as when he meets the Real he sees It with the eye of God. Therefore he rejoices in breaking the fast just as will he rejoice in his fast when he meets his Lord.
(Al-Futuhat al-Makkiyya, Chapter 71)