He did not fast during Ramadhan due to an illness and he died before he could make up for the fast
Question :
A man died on the day of 'Eidul-Fitr, and on the first or second day of Ramadhan he was stricken with an illness. All of Ramadhan passed while he was not fasting. Therefore, do his heirs have to fast on his behalf after his death or do they have to give food or is there nothing due on the deceased and the heirs concerning this?
Answer:
If this sick person broke his fast due to a lack of ability to fast and he was not able to make up for it because he died on the day of 'Eidul-Fitr, then the fast is not obligatory on him to make it for. This is because of his lack of ability due to his illness. He also is not required to make up for the fast because he was not able due to his death on the day of 'Eidul-Fitr. Also, his heirs are not obligated to fast or give food on his behalf.
Source:
The Permanent Committee
Fatawa Islamiyah, Vol. 3 Page 306