Praise be to Allaah.
If she did not fast because she was not able to, then she
has to make up the fasts she has missed in these four years, when she
becomes able to. Allaah says (interpretation of the meaning):
“and whoever is ill or on a journey, the same number
[of days which one did not observe Sawm (fasts) must be made up] from other
days. Allaah intends for you ease, and He does not want to make things
difficult for you. (He wants that you) must complete the same number (of
days), and that you must magnify Allaah [i.e. to say Takbeer (Allaahu Akbar:
Allaah is the Most Great)] for having guided you so that you may be grateful
to Him” [al-Baqarah 2:185]
If there is no hope – according to her doctors – that
she may be cured of her sickness or that her inability to fast will ever be
lifted from her, then she can feed one poor person for every day that she
misses, giving half a saa’ of wheat, dates, rice or whatever her own
family regularly eat in their home. This is like the case of the elderly and
disabled who would be too exhausted by fasting or who find it too difficult
to fast. In this case she does not have to make up the fasts she misses.