Question: A man had upon him an expiation for killing. He fell ill and did not fast, then died. After his death, his son fasted forty days, then broke off the fasting because of illness. What should this son do?
The answer – and Allah is the One who grants success – is that what has become determined upon the deceased is feeding, that is: feeding sixty poor persons. The son must therefore pay from the deceased’s wealth that specified amount. As for the fasting that the son has fasted, it does not suffice for the expiation.
Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2