Reference: Sharh ‘Umdatil-Fiqh – Tape No.7, Question No.14
Question: If a woman [completes her menses and] purifies herself during the day in Ramadhaan, is she required to abstain [from food, drink and all that breaks the fast] for the remainder of the day?
Response: Without a doubt [she must]. Whoever is not fasting [due to a legislated excuse], and then their excuse passes [at some time] during the day, then they are required to abstain [from food, drink and all that breaks the fast] for the remainder of the day – [doing so] out of respect for [the sanctity of] the time [Ramadhaan], and then make-up the fast for this day [after Ramadhaan has passed].
For example, when the traveller completes his journey during the day [in Ramadhaan], and the one who is sick fully recovers during the day, and the menstruating woman [who completes her menses and] purifies herself during the day – [so] all of these [categories of people] are required to abstain [from food, drink and all that breaks the fast] for the remainder of the day out of respect for [the sanctity of] the time [Ramadhaan].
[The same principle applies even to] the young child who attains puberty, and the disbeliever who embraces Islaam during the day – they are required to abstain [from food, drink and all that breaks the fast] for the remainder of the day, and then make-up the fast for this day [after Ramadhaan has passed].