Feeding the Poor as Kaffaars even though One has the Strength to fast

Q: Saum-44: A person has the strength to observe sixty fasts as Kaffaara, yet he chose to feed sixty poor people. Is the Kaffaara valid or must he still fast?

Answer: When a person has the strength to fast, he will have to fast and feeding sixty poor people will not suffice. The feeding may be done if the person cannot fast due to illness or old age. Umdatul Fiqh (Vo1.3 Pg.286) clarifies that in the case where one is unable to free a slave, one needs to fast for two consecutive months and it is only when this is also not possible that one will be allowed to feed sixty poor people. And Allaah knows best what is most correct.

Fatawa Rahimiyyah vol.3