These are the verses that make the fast of Ramadan an obligation, 'as it was prescribed for those before you'. They also give exemptions for the sick and travellers, and state that Allah intends ease, not hardship. Ramadan is the month in which the Qur'an was first revealed.
Al-Baqarah 2:183–185
Listen on Quran.comيَـٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ كُتِبَ عَلَيْكُمُ ٱلصِّيَامُ كَمَا كُتِبَ عَلَى ٱلَّذِينَ مِن قَبْلِكُمْ لَعَلَّكُمْ تَتَّقُونَ
2:183O you who believe, the fasts have been enjoined upon you as they were enjoined upon those before you, so that you may be God-fearing,
أَيَّامًا مَّعْدُودَٰتٍ ۚ فَمَن كَانَ مِنكُم مَّرِيضًا أَوْ عَلَىٰ سَفَرٍ فَعِدَّةٌ مِّنْ أَيَّامٍ أُخَرَ ۚ وَعَلَى ٱلَّذِينَ يُطِيقُونَهُۥ فِدْيَةٌ طَعَامُ مِسْكِينٍ ۖ فَمَن تَطَوَّعَ خَيْرًا فَهُوَ خَيْرٌ لَّهُۥ ۚ وَأَن تَصُومُوا۟ خَيْرٌ لَّكُمْ ۖ إِن كُنتُمْ تَعْلَمُونَ
2:184for days few in number. However, should any one of you be sick or on a journey, then (he should fast) a number of other days (equal to the missed ones); and those who have the strength, (still, they do not opt for fasting,) on them there is a fidyah (compensation), that is, the feeding of a poor person.Then whoever does good voluntarily, that is better for him. However, that you fast is better for you, if you only knew.
شَهْرُ رَمَضَانَ ٱلَّذِىٓ أُنزِلَ فِيهِ ٱلْقُرْءَانُ هُدًى لِّلنَّاسِ وَبَيِّنَـٰتٍ مِّنَ ٱلْهُدَىٰ وَٱلْفُرْقَانِ ۚ فَمَن شَهِدَ مِنكُمُ ٱلشَّهْرَ فَلْيَصُمْهُ ۖ وَمَن كَانَ مَرِيضًا أَوْ عَلَىٰ سَفَرٍ فَعِدَّةٌ مِّنْ أَيَّامٍ أُخَرَ ۗ يُرِيدُ ٱللَّهُ بِكُمُ ٱلْيُسْرَ وَلَا يُرِيدُ بِكُمُ ٱلْعُسْرَ وَلِتُكْمِلُوا۟ ٱلْعِدَّةَ وَلِتُكَبِّرُوا۟ ٱللَّهَ عَلَىٰ مَا هَدَىٰكُمْ وَلَعَلَّكُمْ تَشْكُرُونَ
2:185The month of Ramadan is the one in which the Qur’ān was revealed as guidance for mankind, and as clear signs that show the right way and distinguish between right and wrong. So those of you who witness the month must fast in it. But the one who is sick, or is on a journey (should fast) as much from other days (as he missed). Allah intends (to provide) ease for you and does not intend (to create) hardship for you. All this is so that you may complete the number (of fasts as prescribed) and proclaim the Takbīr of Allah for having guided you, and (so) that you may be grateful.
English translation: Mufti Muhammad Taqi Usmani, The Meanings of the Noble Qur'an, via Quran.com. Arabic: Uthmani script.
What would you gain from giving up something you enjoy for a month?
