The reasoning for this is that whoever catches the opening takbir has caught part of the time, and catching part is like catching all of it, for the prayer is indivisible. This is the well-known position in the school of Imam Ahmad, whether this is caught at the beginning of the time or at its end.

An example of catching it at the beginning of the time is if a woman has enough time for the opening takbir of the sunset prayer, then menstruation begins. We say: she has caught the prayer, so once she becomes pure, she must pray the sunset prayer, because she caught enough of its time for the opening takbir.

An example of catching it at the end of the time is if a woman is menstruating, then becomes pure before sunset with enough time for the opening takbir. In that case, the afternoon prayer becomes obligatory upon her, because she caught enough of the time for the opening takbir. This is with regard to the legal ruling.

With regard to reward, whoever catches the opening takbir within the prayer’s time receives the reward of one who caught the entire prayer, and the prayer counts for him as having been performed on time. Nevertheless, it is not permissible for him to delay the prayer, or any part of it, beyond its time; he is sinful for doing so. Even so, we say that he has caught it as having been performed on time. This is the position of the school.

The second view is that one does not catch the prayer unless one catches a complete unit of prayer (1), based on the Prophet’s saying, may Allah’s peace and blessings be upon him: “Whoever catches one unit of the prayer has caught the prayer.” (2) This view is correct, and it was the view preferred by Shaykh al-Islam