his fast.” Reported by al-Bukhārī. This is a broad subject.
As for reward being proportionate to obedience, obedience to Allah and His Messenger may consist in an easy deed, just as Allah has made the “two phrases” easy for Muslims, although they are the best of deeds. Thus the Prophet, may Allah bless him and grant him peace, said:
“Two phrases are light on the tongue, heavy in the balance, and beloved to the Most Merciful: ‘Glory be to Allah and praise be to Him; glory be to Allah, the Magnificent.’”
Al-Bukhārī and Muslim both related it in their Sahīh collections.
If it were said, “Reward is proportionate to the benefit and usefulness of the deed,” that would be correct. The “former” characterization concerns its relation to the command, and the “latter” its inherent quality. A deed’s benefit and usefulness may derive solely from its being commanded, from its inherent quality, or from both. From the first perspective, deeds are classified as obedience or disobedience; from the second, as good or evil. Obedience and disobedience describe a deed in relation to the command, whereas good and evil describe it in itself. ... (1)
Yet many people affirm only the “first,” as do the Ash'arīs and a group of jurists from our school and others. Some affirm only the “second,” as do the Mu'tazilah and a group