قال تعالى:

‏‏‏ ‏‏‏‏‏ ‏‏‏ ‏‏‏‏ ‏‏‏ ‏‏‏‏‏‏‏ ‏‏‏ ‏‏‏‏‏ ‏‏‏‏‏ ‏‏ ‏‏‏‏‏ ‏‏‏‏‏‏‏‏‏ ‏‏‏ ‏‏‏ ‏‏‏‏ ‏‏‏‏‏ ‏‏‏‏‏‏‏ ‏‏‏ ‏‏ ‏‏‏‏‏ ‏‏ ‏ ‏‏‏ ‏‏‏‏ ‏‏ ‏‏‏‏ ‏‏‏‏ ‏‏‏‏ ‏‏ ‏‏‏ ‏‏‏‏ ‏‏ ‏‏‏‏ ‏‏‏ ‏‏‏‏‏ ‏‏‏‏‏‏‏ ‏‏‏‏‏ ‏‏‏‏‏‏‏‏ ‏‏ ‏ ‏‏ ‏‏‏‏‏ ‏‏‏‏‏‏ ‏‏‏‏‏‏‏ ‏

The month of Ramadhan [is that] in which was revealed the Qur'an, a guidance for the people and clear proofs of guidance and criterion. So whoever sights [the new moon of] the month, let him fast it; and whoever is ill or on a journey - then an equal number of other days. Allah intends for you ease and does not intend for you hardship and [wants] for you to complete the period and to glorify Allah for that [to] which He has guided you; and perhaps you will be grateful.
-البَقَرَة-Al-Baqarah