Sahih al-Bukhari 4505
Narrated 'Ata:
That he heard Ibn `Abbas reciting the Divine Verse:-- 
"And for those who can fast they had a choice either fast, or feed a poor for every day.." (2.184) Ibn 
`Abbas said, "This Verse is not abrogated, but it is meant for old men and old women who have no 
strength to fast, so they should feed one poor person for each day of fasting (instead of fasting).
حَدَّثَنِي إِسْحَاقُ، أَخْبَرَنَا رَوْحٌ، حَدَّثَنَا زَكَرِيَّاءُ بْنُ إِسْحَاقَ، حَدَّثَنَا عَمْرُو بْنُ دِينَارٍ، عَنْ عَطَاءٍ، سَمِعَ ابْنَ عَبَّاسٍ، يَقْرَأُ ‏{‏وَعَلَى الَّذِينَ يُطَوَّقُونَهُ فِدْيَةٌ طَعَامُ مِسْكِينٍ ‏}‏‏.‏ قَالَ ابْنُ عَبَّاسٍ لَيْسَتْ بِمَنْسُوخَةٍ، هُوَ الشَّيْخُ الْكَبِيرُ وَالْمَرْأَةُ الْكَبِيرَةُ لاَ يَسْتَطِيعَانِ أَنْ يَصُومَا، فَلْيُطْعِمَانِ مَكَانَ كُلِّ يَوْمٍ مِسْكِينًا‏.‏