What is the ruling on my sister's fast if she broke it a few moments before the Maghrib call to prayer, thinking that it had already been called, then she did not swallow the bite until she heard the adhan, and what is the ruling on her fast if she had swallowed it?

Scholars differ regarding someone who intends to commit a forbidden act while fasting, such as eating. The Hanbalis are of the view that the fast is invalidated by this intention, while others, such as Ibn Uthaymin, preferred the view that the fast is not invalidated unless the forbidden act is actually committed, because an act of worship is not invalidated merely by the intention to commit a forbidden act within it.

Accordingly, the sister's fast is valid according to the preferred view of Ibn Uthaymin. However, if she ate, thinking the sun had set, there is a difference of opinion regarding the validity of her fast. The opinion that she has not broken her fast in this situation is a strong one, and one who eats thinking the sun has set is not commanded to make up the day, although making it up is more prudent to avoid scholarly disagreement.