because whoever is given a choice regarding an act of worship before entering into it, is also given a choice after entering into it, like fasting. And because shortening is the default, evidenced by the report of ‘A’ishah, ‘Umar, and Ibn ‘Abbas, therefore it does not require an intention, like performing the full prayer (itman) while a resident. The reasoning for the first view is that performing the full prayer is the default, as we will mention in the issue: "The traveler has the choice to shorten and has the choice to perform the full prayer." The unrestricted intention defaults to the primary state and does not deviate from it except by specifying what would divert it, just as if one intended to pray without qualification, not intending to be an imam or a follower, he defaults to praying alone, as that is the default. The subsidiary ruling is based on this view. So, if he doubts during his prayer whether he had intended to shorten at its beginning or not, he must complete it as a precaution because the default is that he did not [intend to shorten]. If he later recalls that he had intended to shorten, he is not permitted to shorten because the duty of completing the prayer has already become binding upon him, and it has not lapsed. If he intended to complete the prayer, or followed a resident, and the prayer became invalid and he wished to repeat it, he is likewise required to complete it because it became binding upon him as a full prayer by his engaging in it behind a resident with the intention of performing it in full. This is the view of al-Shafi‘i. Al-Thawri and Abu Hanifah said: If the imam’s prayer becomes invalid, the traveler returns to his initial state. Our response is that it became binding upon him by entering into it as a full prayer, so it is not permissible for him to shorten it, just as if it had not become invalid.

Section: Whoever intended to shorten, then intended to complete, or intended something that would require him to complete it, such as residing, or changed his intention to a sinful journey, or intended to return from his journey where the return distance does not allow for shortening, or the like, he must complete the prayer, and those behind him must follow him. This is the view of al-Shafi‘i. Malik said: He is not permitted to complete the prayer, because he intended a [specific] number, so if he adds to it, the increase occurs without intention. Our view is that the intention for the prayer of the time has been established, which is four [rak‘ahs], and leaving two rak‘ahs is merely a permitted concession. Thus, if he drops the intention for the concession, the prayer remains valid with its [original] intention, and he is required to complete it. And because completing is the default, and leaving it was only permitted under a condition; when the condition ceases, the default returns to its state.