اَيَّامًا مَّعْدُوْدٰتٍۗ فَمَنْ كَانَ مِنْكُمْ مَّرِيْضًا اَوْ عَلٰى سَفَرٍ فَعِدَّةٌ مِّنْ اَيَّامٍ اُخَرَ ۗ وَعَلَى الَّذِيْنَ يُطِيْقُوْنَهٗ فِدْيَةٌ طَعَامُ مِسْكِيْنٍۗ فَمَنْ تَطَوَّعَ خَيْرًا فَهُوَ خَيْرٌ لَّهٗ ۗ وَاَنْ تَصُوْمُوْا خَيْرٌ لَّكُمْ اِنْ كُنْتُمْ تَعْلَمُوْنَ ( البقرة: ١٨٤ )
Ayyaamam ma'doodaat; faman kaana minkum mareedan aw'alaa safarin fa'iddatum min ayyaamin ukhar; wa 'alal lazeena yuteeqoonahoo fidyatun ta'aamu miskeenin faman tatawwa'a khairan fahuwa khairulo lahoo wa an tasoomoo khairul lakum in kuntum ta'lamoon (al-Baq̈arah 2:184)
[Fasting for] a limited number of days. So whoever among you is ill or on a journey [during them] – then an equal number of other days [are to be made up]. And upon those who are able [to fast, but with hardship] – a ransom [as substitute] of feeding a poor person [each day]. And whoever volunteers good [i.e., excess] – it is better for him. But to fast is best for you, if you only knew. (Al-Baqarah  : 184)
1 Mufti Taqi Usmani
for 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.