In Quran, Allah (swt) has said:

“(Fasting) for a fixed number of days; but if any of you is ill, or on a journey, the prescribed number (Should be made up) 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

Ramadan is the (month) in which was sent down the Quran, as a guide to mankind, also clear (Signs) for guidance and judgment (Between right and wrong). So every one of you who is present (at his home) during that month should spend it in fasting, but if any one is ill, or on a journey, the prescribed period (Should be made up) by days later. Allah intends every facility for you; He does not want to put to difficulties. (He wants you) to complete the prescribed period, and to glorify Him in that He has guided you; and perchance ye shall be grateful.

When My servants ask thee concerning Me, I am indeed close (to them): I listen to the prayer of every supplicant when he calls on Me: Let them also, with a will, Listen to My call, and believe in Me: That they may walk in the right way.

Permitted to you, on the night of the fasts, is the approach to your wives. They are your garments and ye are their garments. Allah knows what ye used to do secretly among yourselves; but He turned to you and forgave you; so now associate with them, and seek what Allah Hath ordained for you, and eat and drink, until the white thread of dawn appear to you distinct from its black thread; then complete your fast Till the night appears; but do not associate with your wives while ye are in retreat in the mosques. Those are Limits (set by) Allah. Approach not nigh thereto. Thus doth Allah make clear His Signs to men: that they may learn self-restraint.”  (Al-Quran: Surah Al-Baqarah 2:184-187)