In order that the incident of the physical fast may be fully understood, more details are given here: ``You have to fast for a certain number of days, but if any one of you is sick or on a journey, has to fast a like number of days in other time.'' As for those who can do the fasting but have to do it with difficulty and hardship, such as the aged or permanently ill people; should know that Allah wants ease for them, and does not want hardship for HIS servants. So they can be redeemed by feeding a poor. OR if he wants to do more of his own accord, instead of feeding a poor much the better. But to take it in a general sense, it is far better for us to do the fasting.