About Ramadan in Al Qur'an

(Fasting) for a fixed number of days; but if any of you is ill, or on
a journey, the prescribed number (Should be madeup) from days later.
For those who can do it (With hardship), is a ransom, the feeding of
one that is indigent. But he that will give more, of his own free
will, it is better for him. And it is better for you that ye fast, if
ye only knew. (2:184)
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O ye who believe! Fasting is prescribed to you as it was prescribed to
those before you, that ye may (learn) self-restraint, (2:183)