the time. [This view] is invalid; for if it were the original, it would be mandatory upon him to perform it, he would be sinful for abandoning it, and the Friday prayer would not suffice him when it is possible. For one does not turn to a substitute except when the original is impossible, as evidenced by all other substitutes compared to the things they substitute. Also, if the Dhuhr prayer were valid, it would not be nullified by setting out for another [prayer], as is the case with all other valid prayers. Additionally, if a prayer is valid, the obligation is cleared, and it removes the duty from the one who performed it, so it is not permissible to occupy oneself with it after that. Furthermore, if a prayer is finished, it is not nullified by any of its nullifiers; so how could it be nullified by that which is not among its nullifiers, and for which no legal text has been revealed? As for when the Friday prayer escapes him, he then turns to Dhuhr, because the Friday prayer cannot be made up (qada'), for it is not valid except with its conditions, and those [conditions] are not found in making it up; thus, it becomes necessary to turn to Dhuhr when [Friday prayer] is absent, and this is the nature of a substitute.

Section: If he performs the Dhuhr prayer, then doubts: Did he perform it before the Imam's prayer or after it? It is binding upon him to repeat it, because the base principle is the persistence of the prayer as a liability upon him, so he is not absolved of it except with certainty. Also, because he performed it while doubting its condition, so it is not valid, just as if he performed it while doubting his state of purity. If he performs it along with the Imam's prayer, it is not valid, because he performed it before the Imam finished it; this is similar to the case where he performs it before him at a time when he knows he will not catch it.

Section: As for those upon whom the Friday prayer is not obligatory, such as the traveler, the slave, the woman, the sick, and other excused people, they may perform the Dhuhr prayer before the Imam's prayer according to the opinion of the majority of scholars. Abu Bakr 'Abd al-'Aziz said: His prayer is not valid before the Imam, because he is not certain that the excuse persists, so his prayer is not valid, like the one who is not excused. Our argument is that he is not addressed to perform the Friday prayer, so Dhuhr is valid from him, just as if he were far from the place of the Friday prayer. Regarding his statement: "He is not certain that the excuse persists," we say: As for the woman, the persistence of her excuse is known, and as for others, the default state is the persistence of their excuse,