يَـٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُواْ كُتِبَ عَلَيۡڪُمُ ٱلصِّيَامُ كَمَا كُتِبَ عَلَى ٱلَّذِينَ مِن قَبۡلِڪُمۡ لَعَلَّكُمۡ تَتَّقُونَ . أَيَّامً۬ا مَّعۡدُودَٲتٍ۬ۚ فَمَن كَانَ مِنكُم مَّرِيضًا أَوۡ عَلَىٰ سَفَرٍ۬ فَعِدَّةٌ۬ مِّنۡ أَيَّامٍ أُخَرَۚ وَعَلَى ٱلَّذِينَ يُطِيقُونَهُ ۥ فِدۡيَةٌ۬ طَعَامُ مِسۡكِينٍ۬ۖ فَمَن تَطَوَّعَ خَيۡرً۬ا فَهُوَ خَيۡرٌ۬ لَّهُ ۥۚ وَأَن تَصُومُواْ خَيۡرٌ۬ لَّڪُمۡۖ إِن كُنتُمۡ تَعۡلَمُونَ. شَہۡرُ رَمَضَانَ ٱلَّذِىٓ أُنزِلَ فِيهِ ٱلۡقُرۡءَانُ هُدً۬ى لِّلنَّاسِ وَبَيِّنَـٰتٍ۬ مِّنَ ٱلۡهُدَىٰ وَٱلۡفُرۡقَانِۚ فَمَن شَہِدَ مِنكُمُ ٱلشَّہۡرَ فَلۡيَصُمۡهُۖ وَمَن ڪَانَ مَرِيضًا أَوۡ عَلَىٰ سَفَرٍ۬ فَعِدَّةٌ۬ مِّنۡ أَيَّامٍ أُخَرَۗ يُرِيدُ ٱللَّهُ بِڪُمُ ٱلۡيُسۡرَ وَلَا يُرِيدُ بِڪُمُ ٱلۡعُسۡرَ وَلِتُڪۡمِلُواْ ٱلۡعِدَّةَ وَلِتُڪَبِّرُواْ ٱللَّهَ عَلَىٰ مَا هَدَٮٰكُمۡ وَلَعَلَّڪُمۡ تَشۡكُرُونَ
"O you who believe! Observing As-Saum (the fasting) is prescribed for you as it was prescribed for those before you, so that you may become Al-Muttaqun (the pious). [Fast] for a fixed number of days, but if any of you is ill or on a journey, the same number (should be made up) from other days. And as for those who can fast with difficulty, (e.g. an old man), they have (a choice either to fast or) to feed a Miskeen (poor person) (for every day). But whoever does good of his own accord, it is better for him. And that you fast, is better for you if only you know.
The month of Ramadan in which was revealed the Qur'an, a guidance for mankind and clear proofs for the guidance and the criterion (between right and wrong). So whoever of you sights (the crescent on the first night of) the month (of Ramadan), he must observe Saum (fasts) that month, and whoever is ill or on a journey, the same number [of days which one did not observe Saum (fasts) must be made up] from other days.
Allah intends for you ease, and He does not want to make things difficult for you. (He wants that you) must complete the same number (of days), and that you must magnify Allah for having guided you so that you may be grateful to Him."
(Qur'an 2: 183-185)