Fasting is for a fixed number of days, and if one of you be sick, or if one of you be on a journey, you will fast the same number of other days later on. For those who are capable of fasting (but still do not fast) there is a redemption: feeding a needy man for each day missed. Whoever voluntarily does more good than is required, will find it better for him; and that you should fast is better for you, if you only know. [2:184]