This is clarified further in the next verse: “if you truly understood,” that is, if you are among those endowed with knowledge and insight.

The point is that fasting is harder for many people than feeding a poor person, and because it is harder it is better. Whenever a servant performs a strenuous act of worship by Allah’s command, the reward is proportionately greater. For that very reason, someone who lives farther from the mosque earns more reward for each step than the one who lives nearby, because he expends more effort. Yet this does not mean that a person should deliberately pursue hardship in acts of worship that Allah has made easy; that would be religious extremism. If, however, Allah charges you with an act of worship and you happen to find it difficult, the reward is indeed greater. What is blameworthy is seeking out hardship, as some ignorant people do in winter: they go and perform ablution with icy water, claiming, “Perfecting ablution despite discomfort raises ranks and erases sins.” We say to them: my brother, this is not what the Messenger ﷺ intended. He only meant that if a person happens to perform ablution with cold water on a winter day, the reward is greater; he did not say, “Look for cold water.” Therefore, if Allah has granted you hot water with which you can perform a complete ablution, that is better.

Allah then says, “So whoever among you is ill…” Illness is of three kinds:

1 – A chronic illness from which recovery is not expected and which is continuous. Such a person is not required to fast but must feed one poor person for every day missed, just like an elderly person who is permanently unable to fast.

2 – An illness that would be worsened by fasting and from which one fears mortal harm