“O you who believe! Prescribed for you is the Fast, as it was prescribed for those before you, so that you may deserve God's protection (against the temptations of your carnal soul) and attain piety.” Sura al-Baqara (2:183)
(Fasting is for) a fixed number of days. If any of you is so ill that he cannot fast, or on a journey, he must fast the same number of other days. But for those who can no longer manage to fast, there is a redemption (penance) by feeding a person in destitution (for each day missed, or giving him the same amount in money). Yet better it is for him who volunteers greater good (by either giving more, or fasting in case of recovery), and that you should fast (when you are able to) is better for you, if you but knew (the worth of fasting). Sura al-Baqara (2:184)
“We have surely sent it (the Qur'ān) down in the Night of Destiny and Power. What will enable you to perceive what the Night of Destiny and Power is? The Night of Destiny and Power is better than a thousand months! The angels and the Spirit descend in it by the permission of their Lord with His decrees in every affair – (Being) absolute mercy and security (from all misfortunes, for the servants who spend it in devotions in appreciation of its worth) (being) until the rising of the dawn.” Sura al-Qadr (97:1-5)