The ability, and the fact that inability to fast is divided into two categories.

The Shaykh : The fourth point is ability, and its opposite is inability. Inability to fast is divided into two categories: temporary inability that is expected to end, such as a common illness, and permanent, continuous inability that is not expected to end, such as illnesses that are not expected to end, like cancer, and old age, because old age is not expected to end, since an elderly person cannot return to youth. This type of inability does not obligate the person to fast, because he is unable to do so. But what does he do? He must feed one poor person for every day. If the month is twenty-nine days, he must feed twenty-nine poor people. If the month is thirty days, he must feed thirty poor people.