Praise be to Allah.
If a woman’s period ends after the time for ‘Isha’ has begun, then she must pray ‘Isha’ because the time for it has come. At the same time, she must also pray Maghrib because it may be put together with ‘Isha’ when there is a valid reason for doing so.
By the same token, if her period ends after the time for ‘Asr has begun, she should pray Zuhr and ‘Asr. This is what was stated in fatwas by some of the companions of the Prophet (blessings and peace of Allah be upon him) and it is the view of the majority of the scholars.
But if she becomes pure after Fajr, or after Zuhr, or after Maghrib, she only has to offer one prayer, which is the prayer at the time of which her period ended (Fajr or Zuhr or Maghrib), because these prayers cannot be put together with the one that comes before them.
Ibn Qudaamah (may Allah have mercy on him) said in al-Mughni (1/238): If a woman’s period ends before the sun sets, she should pray Zuhr, then ‘Asr.
And if her period ends before dawn breaks, she should pray Maghrib and ‘Isha’. This view was narrated from ‘Abd ar-Rahmaan ibn ‘Awf, Ibn ‘Abbaas, Taawoos, Mujaahid, an-Nakha‘i, az-Zuhri, Rabee‘ah, Maalik, al-Layth, ash-Shaafa‘i, Ishaaq and Abu Thawr. Imam Ahmad said: Most of the Taabi‘een followed this view, except al-Hasan only, who said: She only has to offer the prayer at the time of which her period ended. This is the view of ath-Thawri and ashaab ar-ra’y. That is because the time of the first prayer ended when she was still excused, so she does not have to do it, just as if she did not catch up with anything of the time for the second prayer.
It was narrated from Maalik that if there is enough of the time of the second prayer left to do five rak‘ahs, then one must offer the first prayer, because the time needed to do the first of those five rak‘ahs is the time for the first prayer when one has a reason or excuse. Therefore the first prayer becomes obligatory, and will be as if he is doing it at the appropriate time, in contrast to one who does not have enough time to pray five rak‘ahs.
It was narrated by al-Athram, Ibn al-Mundhir and others, with their isnaads from ‘Abd ar-Rahmaan ibn ‘Awf and ‘Abdullah ibn ‘Abbaas, that they said regarding the menstruating woman who becomes pure with enough time before the break of dawn to do one rak‘ah: She should pray Maghrib and ‘Isha’; so if she becomes pure before the sun sets, she should pray Zuhr and ‘Asr, putting them together, because the appropriate time for the later prayer is also the appropriate time for the earlier one, when there is a reason to do that. So one who has that reason at that time must offer the first obligatory prayer just as he must offer the second obligatory prayer. End quote.
It says in Zaad al-Mustaqni‘: If the prayer becomes obligatory for someone before its time ends, then he must offer that prayer and whatever could be put together with it of the previous prayer. End quote.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said in ash-Sharh al-Mumti‘: An example of that is if there is enough of the time of ‘Asr left to pray one rak‘ah, or to say the opening takbeer. In that case he must pray ‘Asr and he must also pray Zuhr. Similarly, if there is enough of the time of ‘Isha’ left, he must pray ‘Isha’ and also pray Maghrib. And if there is enough of the time of Fajr left, he should only pray Fajr, because it cannot be put together with the prayer that comes before it.
If someone asks: What is the evidence that Zuhr becomes obligatory in the first scenario and Maghrib becomes obligatory in the second? The answer is that the evidence is based on reports and rational thinking.
With regard to reports: that was narrated from Ibn ‘Abbaas and ‘Abd ar-Rahmaan ibn ‘Awf (may Allah be pleased with them).
With regard to rational thinking: that is because the time for the later prayer is also the time for the earlier prayer, when there is an excuse that makes it permissible to put the prayers together. As the time for ‘Asr becomes the valid time for Zuhr too when there is a reason, then catching up with part of the time (of the second prayer) is like catching up with part of the time of both of them together. This is the well-known view in our madhhab.
Some of the scholars said: He only has to offer the prayer of which he caught up with its time. As for the prayer that came before it, he does not have to offer it. End quote. The shaykh (may Allah have mercy on him) regarded this view as more likely to be correct.
But to be on the safe side, one should follow the view of the majority of scholars, so she should offer both prayers together, and she does not have to offer the prayers of the entire day. If she limits it to the prayer the time of which she caught up with, we hope that that will be fine.
The woman becomes pure from her menses on the basis of one of two signs: the white discharge or complete dryness, meaning that if she inserts a piece of cotton it will come out clean, with no trace of red or yellow discharge on it, as we explained in the answer to question no. 5595 .
The fact that you wait for one day without praying, because you do not see the white discharge, is not correct, because there is the possibility that you have already become pure, based on dryness. So what you must do is watch for this sign of menses having ended.
An-Nawawi (may Allah have mercy on him) said: The sign of the end of menses and that the woman has become pure is that bleeding and the yellowish and brownish discharges come to an end. When that ends, the woman becomes pure, regardless of whether any white discharge occurs after that or not." (Al-Majmoo‘ 2/562).
And Allah knows best.