Fast for a specified number of days, but if any one among you is ill or on a journey, let him fast the same number of days later. For those who can fast only with extreme difficulty, there is a way to compensate the feeding of a needy person. But he who does good of his own accord shall be well rewarded; but to fast is better for you, if you only knew. (Al Quran al-Baqarah 2:184)