In the name of Allah,
Abu Hurairah (may Allah be pleased with him) reported: The Messenger of Allah (peace be upon him) said, “Allah the Exalted and Majestic said: ‘Every act of the son of Adam is for him, except As-Siyam (the fasting) which is (exclusively) for Me, and I will reward him for it.’[i]
Why is fasting favored over other forms of worship and why is it specifically mentioned here?
Al-Haafiz ibn Hajar (may Allah have mercy on him) cited the opinions of ten scholars who tried to explain what this hadith meant and why fasting was singled out in this way. The most significant are:
No Show-off: Allah, the Most High said, “Every act of the son of Adam is for him, except As- Siyam (fasting) which is (exclusively) for Me.” It means, among other things, that fasting is only for Allah, the Most Powerful. It’s a secret between you and your Lord because it’s the most sincere way to worship. It’s hard to tell if someone is fasting when they’re talking and moving around. This makes it the most sincere way of worship.
Al-Qurtubi said: Showing off may come into all good acts, but only Allaah can see a person fasting, so He linked it to Himself. So, He said in the hadith, “He gives up his desire for Me.”
Unlimited Reward: Some scholars stated that on the Day of Resurrection if a person has harmed other slaves, part of his good acts, except fasting, will be taken for the servants. Since it was intended for Allah Almighty and no one else, it cannot be removed.
The son of Adam is awarded in ten manifolds, except for fasting, which is unmeasured. Al-Qurtubi said: This means that good acts will be repaid between ten and seven hundred times, and as much as Allaah wants, except fasting, which Allaah will reward without measure.
Abu Hurayrah (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Every act of the son of Adam will be rewarded between ten and seven hundred-fold.
Allah said, “Except fasting, for it is for Me and I shall award.”[ii] I’ll award it highly without specifying.
Fasting includes three types of Patience: Patience in obedience to Allah, patience to keep away from Allah’s disobedience, and patience on Allah’s decree.
As for patience in obedience to Allah, a person coerces his soul to fast even though it may detest it due to its difficulty.
Fasting requires patience to refrain from disobeying Allah. He patiently avoids profanity, idle talk, vain talk, and other Allah-prohibited acts.
Patience on Allah’s decree is necessary because fasting causes fatigue, boredom, and thirst, especially on hot days. He’s patient for Allah’s sake[iii]. Allah, the Exalted, has said:
“Only those who are patient shall receive their reward in full, without reckoning” (Az-Zumar: 10).
Most Valuable act of Worship: Fasting is for Me, which means it is the most valuable act of worship to Me.
Ibn ‘Abd al-Barr said, “Fasting is for Me” shows fasting’s supremacy over other worship. Abu Umaamah said that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “You should fast, for there is nothing like it.”[iv]
May Allah’s peace and blessings be on the last prophet
Compiled from the following sources:
Islamqa.info 50388
[i] Sahih al-Bukhari 5927, Sahih Muslim 1151d
[ii] Muslim (115)
[iii] Commentary on Riyaad As-Saaliheen By The Eminent Shaykh Muhammad bin Saalih A l-‘Uthaymeen (may Allah shower blessings on him) Volume 5, Page 291
[iv] Al-Nasaa’i (2220) Saheeh by al-Albaani in Saheeh al-Nasaa’i.